Over four hundred hymns composed by Ephrem still exist.
Granted that some have been lost, Ephrem's productivity is not in doubt.
The church historian Sozomen credits Ephrem with having written over three million lines.
Ephrem combines in his writing a threefold heritage: he draws on the models and methods of early Rabbinic Judaism, he engages skillfully with Greek science and philosophy, and he delights in the Mesopotamian/Persian tradition of mystery symbolism.

The most important of his works are his lyric, teaching hymns (ܡܕܖ̈ܫܐ, madrāšê).
These hymns are full of rich, poetic imagery drawn from biblical sources, folk tradition, and other religions and philosophies.
The madrāšê are written in stanzas of syllabic verse and employ over fifty different metrical schemes.
Each madrāšâ had its qālâ (ܩܠܐ), a traditional tune identified by its opening line.
All of these qālê are now lost.
It seems that Bardaisan and Mani composed madrāšê, and Ephrem felt that the medium was a suitable tool to use against their claims.
 The madrāšê are gathered into various hymn cycles.
Each group has a title — Carmina Nisibena, On Faith, On Paradise, On Virginity, Against Heresies — but some of these titles do not do justice to the entirety of the collection (for instance, only the first half of the Carmina Nisibena is about Nisibis).
Each madrāšâ usually had a refrain (ܥܘܢܝܬܐ, ‘ûnîṯâ), which was repeated after each stanza.
Later writers have suggested that the madrāšê were sung by all-women choirs with an accompanying lyre.

Particularly influential were his Hymns Against Heresies.
Ephrem used these to warn his flock of the heresies that threatened to divide the early church.
He lamented that the faithful were "tossed to and fro and carried around with every wind of doctrine, by the cunning of men, by their craftiness and deceitful wiles."
He devised hymns laden with doctrinal details to inoculate right-thinking Christians against heresies such as docetism.
The Hymns Against Heresies employ colourful metaphors to describe the Incarnation of Christ as fully human and divine.
Ephrem asserts that Christ's unity of humanity and divinity represents peace, perfection and salvation; in contrast, docetism and other heresies sought to divide or reduce Christ's nature and, in doing so, rend and devalue Christ's followers with their false teachings.

Ephrem also wrote verse homilies (ܡܐܡܖ̈ܐ, mêmrê).
These sermons in poetry are far fewer in number than the madrāšê.
The mêmrê were written in a heptosyllabic couplets (pairs of lines of seven syllables each).

The third category of Ephrem's writings is his prose work.
He wrote a biblical commentary on the Diatessaron (the single gospel harmony of the early Syriac church), the Syriac original of which was found in 1957.
His Commentary on Genesis and Exodus is an exegesis of Genesis and Exodus.
Some fragments exist in Armenian of his commentaries on the Acts of the Apostles and Pauline Epistles.

He also wrote refutations against Bardaisan, Mani, Marcion and others.

Ephrem is attributed with writing hagiographies such as The Life of Saint Mary the Harlot, though this credit is called into question.

Ephrem wrote exclusively in the Syriac language, which is a dialect of middle Aramaic, but translations of his writings exist in Classical Armenian, Coptic, Old Georgian, Koine Greek and other languages.
Some of his works are only extant in translation (particularly in Armenian).
Syriac churches still use many of Ephrem's hymns as part of the annual cycle of worship.
However, most of these liturgical hymns are edited and conflated versions of the originals.

The most complete, critical text of authentic Ephrem was compiled between 1955 and 1979 by Dom Edmund Beck, OSB, as part of the Corpus Scriptorum Christianorum Orientalium.

As Chronologist, St. Ephrem the Syrian has composed the history of the Patriarchs and Kings from the Creation to the Crucifixion of Christ, The Book of the Cave of Treasure, translated by W. Budge from the Syriac text of the British Museum Mss Add.
25875, published by The Religious Tract Society,
Over four hundred hymns composed by Ephrem still exist. Granted that some have been lost, Ephrem's productivity is not in doubt. The church historian Sozomen credits Ephrem with having written over three million lines. Ephrem combines in his writing a threefold heritage: he draws on the models and methods of early Rabbinic Judaism, he engages skillfully with Greek science and philosophy, and he delights in the Mesopotamian/Persian tradition of mystery symbolism.
The most important of his works are his lyric, teaching hymns (ܡܕܖ̈ܫܐ, madrāšê). These hymns are full of rich, poetic imagery drawn from biblical sources, folk tradition, and other religions and philosophies. The madrāšê are written in stanzas of syllabic verse and employ over fifty different metrical schemes. Each madrāšâ had its qālâ (ܩܠܐ), a traditional tune identified by its opening line. All of these qālê are now lost. It seems that Bardaisan and Mani composed madrāšê, and Ephrem felt that the medium was a suitable tool to use against their claims.  The madrāšê are gathered into various hymn cycles. Each group has a title — Carmina Nisibena, On Faith, On Paradise, On Virginity, Against Heresies — but some of these titles do not do justice to the entirety of the collection (for instance, only the first half of the Carmina Nisibena is about Nisibis). Each madrāšâ usually had a refrain (ܥܘܢܝܬܐ, ‘ûnîṯâ), which was repeated after each stanza. Later writers have suggested that the madrāšê were sung by all-women choirs with an accompanying lyre.
Particularly influential were his Hymns Against Heresies. Ephrem used these to warn his flock of the heresies that threatened to divide the early church. He lamented that the faithful were "tossed to and fro and carried around with every wind of doctrine, by the cunning of men, by their craftiness and deceitful wiles." He devised hymns laden with doctrinal details to inoculate right-thinking Christians against heresies such as docetism. The Hymns Against Heresies employ colourful metaphors to describe the Incarnation of Christ as fully human and divine. Ephrem asserts that Christ's unity of humanity and divinity represents peace, perfection and salvation; in contrast, docetism and other heresies sought to divide or reduce Christ's nature and, in doing so, rend and devalue Christ's followers with their false teachings.
Ephrem also wrote verse homilies (ܡܐܡܖ̈ܐ, mêmrê). These sermons in poetry are far fewer in number than the madrāšê. The mêmrê were written in a heptosyllabic couplets (pairs of lines of seven syllables each).
The third category of Ephrem's writings is his prose work. He wrote a biblical commentary on the Diatessaron (the single gospel harmony of the early Syriac church), the Syriac original of which was found in 1957. His Commentary on Genesis and Exodus is an exegesis of Genesis and Exodus. Some fragments exist in Armenian of his commentaries on the Acts of the Apostles and Pauline Epistles.
He also wrote refutations against Bardaisan, Mani, Marcion and others.
Ephrem is attributed with writing hagiographies such as The Life of Saint Mary the Harlot, though this credit is called into question.
Ephrem wrote exclusively in the Syriac language, which is a dialect of middle Aramaic, but translations of his writings exist in Classical Armenian, Coptic, Old Georgian, Koine Greek and other languages. Some of his works are only extant in translation (particularly in Armenian). Syriac churches still use many of Ephrem's hymns as part of the annual cycle of worship. However, most of these liturgical hymns are edited and conflated versions of the originals.
The most complete, critical text of authentic Ephrem was compiled between 1955 and 1979 by Dom Edmund Beck, OSB, as part of the Corpus Scriptorum Christianorum Orientalium.
As Chronologist, St. Ephrem the Syrian has composed the history of the Patriarchs and Kings from the Creation to the Crucifixion of Christ, The Book of the Cave of Treasure, translated by W. Budge from the Syriac text of the British Museum Mss Add. 25875, published by The Religious Tract Society, 
Ephrem the Syrian