Progression from normotension between 1964 and 1972 to essential hypertension by age 55 years was documented in 1,031 adult members of the Kaiser Permanente Medical Care Program (Northern California region) from computerized multiphasic health checkup records and medical record review. Each case was matched to a persistently normotensive control on age, sex, race, number, and dates of multiphasics. In 609 pairs with baseline measurements of subscapular and triceps skinfolds, mean interval from baseline to the case's first hypertensive multiphasic was 5.7 years, and mean age at onset of hypertension was 47 years. Baseline measures of body mass index, subscapular skinfold, and triceps skinfold were each predictive of development of hypertension (odds ratios 3.85, 3.75, and 2.29 respectively, comparing highest with lowest quintiles, p less than 0.0001 for each). When both skinfolds were included in the same model, subscapular skinfold was highly predictive and triceps skinfold was no longer related to risk. When the authors controlled for overall obesity (body mass index), subscapular skinfold remained highly predictive (p less than 0.0001). In 330 pairs who also had skinfold measurements at the hypertensive multiphasic, weight gain was a strong predictor of hypertension. Increase in subscapular skinfold conferred a small increase in risk in women only. The authors conclude that centrally deposited body fat increases risk for developing essential hypertension independent of the overall level of obesity, while peripherally deposited fat does not.