Leoni Neumann Claman was the daughter of Ignac Neumann, a physician of Hungarian birth, and his wife Flora Vogel Neumann. She studied at Hunter College and entered the Columbia University College of Physicians & Surgeons (P&S) in 1920, only three years after it had opened its doors to women.

She received her medical degree in 1924 and then completed an internship at Bellevue Hospital. Though she planned to be a surgeon, Claman temporarily retired from medicine after marrying Irving Claman, a 1923 graduate of P&S. After having four children, she returned to medicine as an allergist. After training with Robert A. Cooke, she assumed a prominent role in New York City allergy medicine. She directed the Physical Fitness Center for Asthmatic Children for many years and served as Chairman of the Allergy Foundation of America and President of the New York Allergy Association. She died in 1989.