Born in Kupiškis, Lithuania in 1914, he studied alongside some of the most prominent and revered Jewish leaders and rabbis of his time, most notably Rabbi Avraham Duber Kahana Shapiro (author of Devar Avraham). When the Nazis invaded Kaunas in 1941 during World War II, Oshry's community was forced into the Kaunas Ghetto and Concentration Camp.
In his book, The Annihilation of Lithuanian Jewry, Oshry tells his story of living through the Holocaust. Besides the horrific details of how the Nazis and their Lithuanian collaborators viciously murdered Jews, Oshry focuses on the spiritual life of the Jews living in the Kaunas Ghetto and Concentration Camp; these tortured Jews, despite being starved and beaten, continued to study Torah in secret and to risk their lives in order to fulfill God's commandments.
While in the Kaunas Ghetto and Concentration Camp, Oshry began writing his responsa regarding the Holocaust, answering very difficult questions concerning human nature, God, and Jewish ethics. Before the final battle between the Nazis and the Soviets, Oshry buried his responsa in the ground. After the war, he retrieved them and ultimately - in 1959 - he published some of those Hebrew responsa under the title: She'eilos Uteshuvos Mima'amakim (Questions and Responses from the Depths). This volume was later followed by four additional volumes - the final one being published in 1979. [Below in "External links" find a link to each of the five original Hebrew volumes.] An English volume of the original work [adbridged; much of the halakhic argumentation removed], was published titled: Responsa from the Holocaust.
After Kaunas was liberated in August 1944, Oshry and his wife Frieda Greenzwieg, a survivor of Auschwitz, went to Rome. There Oshry started a yeshiva for orphaned refugee children. In 1950 he brought with him all of his yeshiva students when he and his family moved to Montreal. They came to New York in 1952 where Oshry became the rabbi of Beth Hamedrash Hagodol. Oshry opened a boy's yeshiva and a girl's yeshiva in the East Bronx. Also Yeshiva Shaar Ephraim in Monsey is named after him and is run by Oshry's son-in-law.
- “Rabbi Ephraim Oshry, 89, led Norfolk St. temple”, The Villager (New York), vol. 73, No. 22, dated October 1–7, 2003.
- Amateau, Albert. "Rabbi Ephraim Oshry, 89, religious scholar, dies", Downtown Express, Volume 16, Issue 19, October 7–13, 2003.
- Oshry, Ephraim. Annihilation of Lithuanian Jewry, Judaica Press, 1995 ISBN 978-1-880582-18-3
- Oshry, Ephraim. Responsa from the Holocaust, B. Goldman and Y. Leiman Eds., Judaica Press, 2001 ISBN 978-1-880582-71-8