We describe the 40-year weight history and adult morbidity and mortality in a cohort of 504 overweight children, aged 2 months to 16 years, who were admitted for investigation of their overweight to four children's hospitals in Stockholm between 1921 and 1947. Follow-up information was gathered by questionnaire at 10-year intervals, most recently in 1980-1983 (n = 458), on weight history (based on the body mass index (BMI = kg/m2)), as well as prevalence of cardiovascular disease (n = 143), diabetes (n = 39), and cancer (all types (n = 20)), reported during the 40 years of follow-up, and mortality from all causes (n = 55), determined from death certificate. The sample of overweight children remained overweight as adults; after age 55 years, the BMI began to decline for both genders. Female subjects were heavier than their male counterparts from postpuberty onward. Subjects who died by the 40-year follow-up and those reporting cardiovascular disease were significantly (P < or = 0.05) heavier at puberty and in adulthood than were healthier subjects. There was a marked increase in the BMI between postpuberty and age 25 among those who subsequently died, those who developed cardiovascular disease, and particularly among those who developed diabetes (P < or = 0.001). In contrast, those reporting cancer had a lower BMI throughout adulthood than those who did not. We conclude that overweight in adolescence may continue into adulthood and may be associated with subsequent adverse health outcomes.