Flossie Cohen pushed the boundaries of pediatric medicine throughout her career, from providing bone marrow transplants to creating a pediatric AIDS center. Born in India, Cohen trained at the University of Buffalo, where she was one of six women in the graduating class of 1950. After a residency in pediatrics at the Jewish Hospital of Brooklyn, she joined the staff of the Children’s Hospital of Michigan in 1953 and began researching pediatric immunology and the passage of red blood cells between fetuses and their mothers. She helped create Children’s Hospital’s Clinical Immunology Laboratory and Clinical Immunology/Rheumatology Service, both of which she directed until 1992. In 1975 Cohen performed the first successful pediatric bone marrow transplant in Michigan. In 1985 she created the hospital’s Pediatric HIV Clinic, and in 1991 earned the clinic an NIH contract for prenatal and pediatric AIDS clinical trials. Alongside her clinical and administrative work, Cohen taught at Wayne State University’s School of Medicine.