Dr. Yehuda Nir was born Juliusz Gruenfeld to a Jewish family in Lvov, Poland (now Ukraine). Their comfortable life was upended in 1941, when the Germans invaded their part of eastern Poland in World War II, which had previously been occupied by the Soviets. With their Ukrainian collaborators, the Germans began mass roundups and executions of Jewish men, including his father. Young Yehuda, his mother and his older sister, Lala, obtained forged papers identifying them as Roman Catholics, and decided to make their way to another city, where no one would recognize them. They went first to Krakow, then to Warsaw. The family was forced into labor on a German farm, but survived and eventually were freed by the advancing Red Army. They emigrated to the British Mandate of Palestine, where he changed his name and taught himself English by practicing lines from Macbeth. Although his education had stopped at the fifth grade level, he eventually managed to enter Hebrew University Hadassah Medical School and also studied at medical school in Vienna. He emerged from the war with a deep sense of the injustice that had been done to his family and a mission to heal the impact of trauma in others — what is known today as post-traumatic stress disorder. He did groundbreaking work in the psychological treatment of terminally ill children and also studied how the suffering of parents is transmitted to their children. Many of his patients in private practice were Holocaust survivors or the children of survivors. His approach to treatment often had its roots in his own daily wartime terror, as chronicled in his 1989 memoir, The Lost Childhood: The Complete Memoir. Dr. Nir came to the USA in 1959 for his medical residency and remained, but was still fervently engaged with Israel. He served as a chief of child psychiatry at Memorial Sloan-Kettering Cancer Center from 1979 to 1986. In 1973, he married as his second wife Dr. Bonnie Maslin, a psychologist with whom he wrote a number of self-help books on relationships. Their daughter Sarah Maslin Nir became a reporter for The New York Times.