OBJECTIVE The aim of this study was to investigate the relationship between the blood pressure response and body fat in patients treated with the calcium entry blocker nifedipine. METHODS Forty untreated subjects with moderate hypertension completed the study. METHODS Height, weight, body mass index (BMI) and body fat (measured by near infrared spectrophotometry using Futrex 5000) were measured before the start of the study. Based on blood pressure measurements before and 30 min after one capsule of 10 mg nifedipine, the patients were allocated to treatment with 10 mg nifedipine daily in the responder group (reduction in diastolic blood pressure > or = 10 mmHg) and with 20 mg nifedipine daily in the non-responder group. Finally, the blood pressure was measured after 1 week. RESULTS Twelve patients were classified as responders and 28 patients as non-responders. The responder/non-responder groups were comparable with respect to the blood pressure readings initially and to age, whereas the non-responders had higher weight (P < 0.01) and BMI (P < 0.01), more body fat (P < 0.01) and were smaller in height (P < 0.01). After 1 week no additional antihypertensive effect was observed in either group. The blood pressure reduction was negatively correlated to the body fat mass in kilogrammes (P < 0.05 for systolic and P < 0.01 for diastolic blood pressure) in the responder group but not in the non-responder group, whereas no significant correlations were found to BMI in either group. CONCLUSIONS Our data indicate that the body fat can be used to predict the antihypertensive effect of nifedipine.