Stewart Rahr was raised in a Jewish family in Far Rockaway section of Queens, New York. He has an older brother, Elliot. As a youth, he worked at his father's Retail pharmacy store in Brooklyn and in 1963, he graduated from Poly Prep Country Day School also in Brooklyn. He graduated with a B.A. from New York University and attended New York University Law School before dropping out to take over his family's pharmacy Business which then had $50,000 in sales.