To estimate the changes in the prevalence of hypertension and associated risk factors over a 30 years period a cross-sectional population survey in three randomly selected sectors of Chandigarh city was carried out. Study population consisted of 1181 individuals (570 males and 611 females) aged 35 years and above. A total of 1049 subjects were interviewed using a structured interview schedule, and 937 were examined by a physician. Blood pressure and anthropometric measurements were recorded. Physical activity was graded according to the job performed by the individual. Guidelines of the Fifth Joint National Committee (JNC-V) of USA were used for diagnosis of hypertension. Estimation of body fat from skin fold thickness was done by applying Grande's formula and the method of Pascale et al. Data were compared to that of year 1968 when a similar cross-sectional survey had been carried out in Chandigarh. Age and sex standardised prevalence of hypertension according to JNC-V criteria increased from 26.9 per cent in 1968 to 44.9 per cent in 1996-97. In 1968, 70% of the male population were engaged in sedentary and light physical activity compared to 73.7 per cent in 1996-97. Total body fat has increased in both men and women. High and high middle income groups in males were 61.2% in 1996-97 compared to 37.4% in 1968. Smoking rates, however, remained unchanged, 25.4 per cent men smoked in 1968 compared to 24.6 per cent in 1996-97. The prevalence of hypertension has almost doubled over 30 years in Chandigarh. Unfavourable change in prevalence of hypertension, physical activity and body fat makes this population highly vulnerable to cardiovascular morbidity and mortality.