A community based epidemiological study of hypertension was carried out on a random urban sample of young persons (15-24 yr) of Delhi. Hypertension was defined as systolic blood pressure greater than 140 mmHg and/or a diastolic blood pressure greater than 85 mm Hg or a history of current antihypertensive therapy. Of the 6543 subjects examined, 202 were found to be hypertensive. The overall prevalence rate was 30.9/1000 (male 41.2/1000, female 21.7/1000). Secondary hypertension was present in 4 of the 202 patients. Only 16 patients were aware of the presence of hypertension; of these 6 were on medication. Family history of hypertension was present in 87 subjects (43.1%). Of the 202 hypertensives, 67 were obese and 16 were smokers. The degree of physical activity was identical in the hypertensive and non-hypertensive subjects. Blood samples of 129 of the 202 patients were analysed for lipid levels. High values of total cholesterol were observed in nine.