Falloppio's own work dealt mainly with the anatomy of the head.
He added much to what was known before about the internal ear and described in detail the tympanum and its relations to the osseous ring in which it is situated.
He also described minutely the circular and oval windows (fenestræ) and their communication with the vestibule and cochlea.
He was the first to point out the connection between the mastoid cells and the middle ear.
His description of the lacrimal ducts in the eye was a marked advance on those of his predecessors and he also gave a detailed account of the ethmoid bone and its cells in the nose.
His contributions to the anatomy of the bones and muscles were very valuable.
It was in myology particularly that he corrected Vesalius.
He studied the reproductive organs in both sexes, and described the Fallopian tube, which leads from the ovary to the uterus and bears his name to this day.

The aquaeductus Fallopii, the canal through which the facial nerve passes after leaving the auditory nerve, is also named after him.
Falloppio’s contributions to neuroanatomy, however, are still of interest today due to attempts to better understand the structures he first found.
He was interested in the sensory systems in the face.
He centered his research on understanding the path of the nerves of the face and structures that lie in their tracks.
Here, he left his name to two parts of the human face, only emphasizing his enormous influence on the study of the head.
The facial canal was first described by Falloppio, who studied its path, structure, and contents.
He also described the Fallopian hiatus, an opening in the anterosuperior part of the petrosal bone.

His contributions to practical medicine were also important.
He was the first to use an aural speculum for the diagnosis and treatment of diseases of the ear, and his writings on surgical subjects are still of interest.
He published two treatises on ulcers and tumors, a treatise on surgery, and a commentary on Hippocrates's book on wounds of the head.
In his own time he was regarded as somewhat of an authority in the field of sexuality.
Fallopio was the first to describe a condom (in his writings, a linen sheath wrapped around the penis), and he advocated the use of such sheaths to prevent syphilis.
In an early example of a clinical trial, Falloppio reported that he tested these condoms in 1,100 men, none of whom contracted syphilis.
Falloppio was also interested in every form of therapeutics.
He wrote a treatise on baths and thermal waters, another on simple purgatives, and a third on the composition of drugs.
None of these works, except his Anatomy (Venice, 1561), were published during his lifetime.
As we have them, they consist of manuscripts of his lectures and notes of his students.
They were published by Volcher Coiter (Nuremberg, 1575).

Falloppio argued against Fracastoro's theory of fossils, as described as follows in Charles Lyell's Principles of Geology: 
Falloppio of Padua conceived that petrified shells had been generated by fermentation in the spots where they were found, or that they had in some cases acquired their form from 'the tumultuous movements of terrestrial exhalations.'
Although a celebrated professor of anatomy, he taught that certain tusks of elephants dug up in his time at Puglia were mere earthy concretions, and, consistently with these principles, he even went so far as to consider it not improbable, that the vases of Monte Testaceo at Rome were natural impressions stamped in the soil.
Falloppio's own work dealt mainly with the anatomy of the head. He added much to what was known before about the internal ear and described in detail the tympanum and its relations to the osseous ring in which it is situated. He also described minutely the circular and oval windows (fenestræ) and their communication with the vestibule and cochlea. He was the first to point out the connection between the mastoid cells and the middle ear. His description of the lacrimal ducts in the eye was a marked advance on those of his predecessors and he also gave a detailed account of the ethmoid bone and its cells in the nose. His contributions to the anatomy of the bones and muscles were very valuable. It was in myology particularly that he corrected Vesalius. He studied the reproductive organs in both sexes, and described the Fallopian tube, which leads from the ovary to the uterus and bears his name to this day.
The aquaeductus Fallopii, the canal through which the facial nerve passes after leaving the auditory nerve, is also named after him. Falloppio’s contributions to neuroanatomy, however, are still of interest today due to attempts to better understand the structures he first found. He was interested in the sensory systems in the face. He centered his research on understanding the path of the nerves of the face and structures that lie in their tracks. Here, he left his name to two parts of the human face, only emphasizing his enormous influence on the study of the head. The facial canal was first described by Falloppio, who studied its path, structure, and contents. He also described the Fallopian hiatus, an opening in the anterosuperior part of the petrosal bone.
His contributions to practical medicine were also important. He was the first to use an aural speculum for the diagnosis and treatment of diseases of the ear, and his writings on surgical subjects are still of interest. He published two treatises on ulcers and tumors, a treatise on surgery, and a commentary on Hippocrates's book on wounds of the head. In his own time he was regarded as somewhat of an authority in the field of sexuality. Fallopio was the first to describe a condom (in his writings, a linen sheath wrapped around the penis), and he advocated the use of such sheaths to prevent syphilis. In an early example of a clinical trial, Falloppio reported that he tested these condoms in 1,100 men, none of whom contracted syphilis. Falloppio was also interested in every form of therapeutics. He wrote a treatise on baths and thermal waters, another on simple purgatives, and a third on the composition of drugs. None of these works, except his Anatomy (Venice, 1561), were published during his lifetime. As we have them, they consist of manuscripts of his lectures and notes of his students. They were published by Volcher Coiter (Nuremberg, 1575).
Falloppio argued against Fracastoro's theory of fossils, as described as follows in Charles Lyell's Principles of Geology: 
Falloppio of Padua conceived that petrified shells had been generated by fermentation in the spots where they were found, or that they had in some cases acquired their form from 'the tumultuous movements of terrestrial exhalations.' Although a celebrated professor of anatomy, he taught that certain tusks of elephants dug up in his time at Puglia were mere earthy concretions, and, consistently with these principles, he even went so far as to consider it not improbable, that the vases of Monte Testaceo at Rome were natural impressions stamped in the soil.
Gabriele Falloppio