Denise Kandel (German: [ˈkandəl]; née Bystryn; born February 27, 1933) is an American medical sociologist and epidemiologist, Professor of Sociomedical Sciences and Psychiatry at Columbia University and Head of the Department of Epidemiology of Substance Abuse at the New York State Psychiatric Institute. She is known for her epidemiological longitudinal studies on the sequence of first-time use of various legal and illegal drugs, carried out beginning in the 1970s and continuing until at least 2016.