Rabbi Avraham Tzvi (Hirsch) Kamai was born in 1860 in Shkud, Lithuania, the son of Rabbi Eliyahu Baruch Kamai, later rabbi of Mir and head of its famous yeshiva. He learned Torah from his father and showed great ability from a young age.

After his marriage he turned down the rabbinic posts he was offered and, to support his family, opened a pharmacy while continuing to learn. In 1911 the community of Keidan chose him as its rabbi; he agreed only on condition that he would live from the pharmacy rather than from the rabbinate. The Jews of Keidan were expelled in 1915, and he wandered in Ukraine until the end of the First World War.

When his father died, he agreed to succeed him as rabbi of Mir. When the yeshiva returned to the town in 1921, he worked to rebuild it after the hardships of the war.

On 19 Cheshvan 5702 (9 November 1941) the Nazis led him, his family and some 1,200 Jews of Mir to a nearby forest, where they were shot and buried in a mass grave. Most of his writings were burned; a few of his chiddushim were printed at the end of Divrei Eliezer by his brother-in-law, Rabbi Eliezer Yehuda Finkel.