Moshe Wallach was one of seven children born to Joseph Wallach (1841–1921), a textile merchant originally from Euskirchen, and Marianne Levy of Münstereifel.
His parents moved to Cologne following their marriage in 1863.
Joseph Wallach was a founder of Adass Jeshurun, the Cologne Orthodox community, which he later served as president.

In his youth, Wallach attended the Friedrich-Wilhelm-Gymnasium, Cologne and a Jewish school run by the Cologne Orthodox community.
He studied medicine at the University of Berlin and University of Würzburg, and received his Doctor of Medicine degree in 1889.
In 1890 he was chosen by the Frankfurt-based Jewish Conference for the Support of the Jews in Palestine to emigrate to Palestine and carry out its plans to open a modern Jewish hospital in Jerusalem.
Wallach first opened a clinic and pharmacy in the Armenian Quarter of the Old City.
He also worked in the Bikur Holim Hospital as a women's and children's physician, ophthalmologist, and surgeon specializing in neck surgery.
He was the first to perform tracheotomies in Jerusalem, and performed many ritual circumcisions.

In 1896 Wallach returned to Europe to raise funds for the new hospital, collecting donations in Germany and Holland.
Upon his return to Jerusalem, he purchased a 10-dunam (2.5 acre) plot of land located 3 kilometres (1.9 mi) outside the Old City Walls on what would become Jaffa Road.
He registered the land in his own name with the help of the German consul in Jerusalem, Dr. Paul von Tischendorf, who also helped him procure building materials from Germany.

Shaare Zedek Hospital opened on January 27, 1902 with 20 beds, an outpatient clinic, and a pharmacy.
With most of the hospital's patients living in the Old City, a 20-minute donkey ride away, and a dearth of in-house staff, Wallach often made house calls to determine whether a case actually warranted hospitalization.
If transporting to the hospital would be dangerous, he performed curettage; otherwise, he accompanied the patient on a stretcher back to the hospital surgery.

In addition to departments for internal medicine, maternity and children, Wallach later opened an infectious diseases department which was the only one in Jerusalem to treat polio.
During the milk shortages of World War I, Wallach bought several milk cows and built a cowshed and grazing field for them behind the hospital.
The herd was gradually increased to 40 cows and became a source of revenue, especially for kosher-certified milk sales for Passover.

Wallach, who for several decades was the only in-house physician at Shaare Zedek, ran the hospital as a strictly Orthodox institution.
He insisted on strict Sabbath observance and a high level of kashrut in the hospital, and personally supervised the milking of the cows.
He arranged for an electric generator to service the hospital so that it would not have to rely on electricity provided by the power station, where Jews worked on Shabbat.
He set aside part of the field adjacent to the hospital to the growing of wheat for shemura matzo and supervised the baking of matzos for Passover.
For Sukkot, he erected a 10 metres (33 ft) by 4 metres (13 ft) sukkah in the hospital courtyard to accommodate both eating and sleeping.

The language of the hospital was German or Yiddish; Wallach refused to speak in Hebrew, the language of Torah study, in a secular institution.
Before the rise of Nazism, Wallach ordered all hospital correspondence to be conducted in German; afterwards he allowed letters to be written in Rashi script, a Hebrew typeface.
Moshe Wallach was one of seven children born to Joseph Wallach (1841–1921), a textile merchant originally from Euskirchen, and Marianne Levy of Münstereifel. His parents moved to Cologne following their marriage in 1863. Joseph Wallach was a founder of Adass Jeshurun, the Cologne Orthodox community, which he later served as president.
In his youth, Wallach attended the Friedrich-Wilhelm-Gymnasium, Cologne and a Jewish school run by the Cologne Orthodox community. He studied medicine at the University of Berlin and University of Würzburg, and received his Doctor of Medicine degree in 1889. In 1890 he was chosen by the Frankfurt-based Jewish Conference for the Support of the Jews in Palestine to emigrate to Palestine and carry out its plans to open a modern Jewish hospital in Jerusalem. Wallach first opened a clinic and pharmacy in the Armenian Quarter of the Old City. He also worked in the Bikur Holim Hospital as a women's and children's physician, ophthalmologist, and surgeon specializing in neck surgery. He was the first to perform tracheotomies in Jerusalem, and performed many ritual circumcisions.
In 1896 Wallach returned to Europe to raise funds for the new hospital, collecting donations in Germany and Holland. Upon his return to Jerusalem, he purchased a 10-dunam (2.5 acre) plot of land located 3 kilometres (1.9 mi) outside the Old City Walls on what would become Jaffa Road. He registered the land in his own name with the help of the German consul in Jerusalem, Dr. Paul von Tischendorf, who also helped him procure building materials from Germany.
Shaare Zedek Hospital opened on January 27, 1902 with 20 beds, an outpatient clinic, and a pharmacy. With most of the hospital's patients living in the Old City, a 20-minute donkey ride away, and a dearth of in-house staff, Wallach often made house calls to determine whether a case actually warranted hospitalization. If transporting to the hospital would be dangerous, he performed curettage; otherwise, he accompanied the patient on a stretcher back to the hospital surgery.
In addition to departments for internal medicine, maternity and children, Wallach later opened an infectious diseases department which was the only one in Jerusalem to treat polio. During the milk shortages of World War I, Wallach bought several milk cows and built a cowshed and grazing field for them behind the hospital. The herd was gradually increased to 40 cows and became a source of revenue, especially for kosher-certified milk sales for Passover. 
Wallach, who for several decades was the only in-house physician at Shaare Zedek, ran the hospital as a strictly Orthodox institution. He insisted on strict Sabbath observance and a high level of kashrut in the hospital, and personally supervised the milking of the cows. He arranged for an electric generator to service the hospital so that it would not have to rely on electricity provided by the power station, where Jews worked on Shabbat. He set aside part of the field adjacent to the hospital to the growing of wheat for shemura matzo and supervised the baking of matzos for Passover. For Sukkot, he erected a 10 metres (33 ft) by 4 metres (13 ft) sukkah in the hospital courtyard to accommodate both eating and sleeping.
The language of the hospital was German or Yiddish; Wallach refused to speak in Hebrew, the language of Torah study, in a secular institution. Before the rise of Nazism, Wallach ordered all hospital correspondence to be conducted in German; afterwards he allowed letters to be written in Rashi script, a Hebrew typeface.
Moshe Wallach