In 1946, Dr. Leonidas Harris Berry became the first black physician on staff at Michael Reese Hospital in Chicago. On December 20, 1963, after being refused attending physician status for seventeen years, Reese Hospital named Berry to its attending staff. For the rest of his career, Berry held the position of senior attending physician at Michael Reese Hospital.

In 1970, he helped organize the Flying Black Medics, a group of practitioners who flew from Chicago to Cairo to bring medical care and health education to members of the remote community.