OBJECTIVE: The authors sought to determine the association between mental disorder and morbid obesity, defined as weight at least 100% or 100 lb over ideal body weight. METHOD: Eighty-eight morbidly obese subjects who had come to a tertiary care center surgery clinic requesting vertical banded gastroplasty were systematically interviewed with the National Institute of Mental Health Diagnostic Interview Schedule (DIS) and the Structured Interview for DSM-III Personality Disorders. A comparison group of 76 psychiatrically normal subjects who were matched in age (within 5 years) and gender to the morbidly obese subjects were also interviewed. RESULTS: Most of the morbidly obese subjects were women, were of low socioeconomic status as indicated by method of payment for medical care, weighed more than 300 lb, and had been obese for more than 14 years. The morbidly obese subjects were more likely than the comparison group to have a lifetime history of mood disorders, anxiety disorders, bulimia, and tobacco dependence. The morbidly obese subjects were also more likely to meet diagnostic criteria for one or more personality disorders. CONCLUSIONS: Substantial psychopathology exists in morbidly obese individuals requesting gastroplasty, a finding that has important clinical implications.Abstract Teaser