OBJECTIVES--The objective of the study was to establish the prevalence of hypertension and to assess determinants of blood pressure with special reference to socioeconomic status in a rural south Indian community. DESIGN--This was a door to door, cross sectional survey. SETTING--A rural south Indian community, KV Kuppam panchayat, North Arcot District, Tamil Nadu. SUBJECTS--The area has a total population of 3500 people. Those aged over 20 years who were available at the time of measurement were asked to participate (mean age 39.5 years). This convenience sample totalled 1027 (456 men, 571 women). Out of 697 families, 487 were visited; 15 people refused to participate. MEASUREMENTS AND MAIN RESULTS--The following potential determinants of blood pressure were assessed: age, body weight, pulse rate, salt intake, meat intake, and socioeconomic class. The prevalence of hypertension was 12.5%. Using multiple linear regression analysis, the most important positive determinants of high blood pressure seemed to be age, body weight, and pulse rate. Salt and meat intake were not significantly associated with hypertension. The prevalence of hypertension in the highest socioeconomic group (22.5%) was more than twice that in the lowest socioeconomic group (8.8%). When adjusted for body weight, the mean (SEM) difference in systolic blood pressure between the highest and lowest socioeconomic classes was 5.83 mmHg (1.63). CONCLUSION--Hypertension is not yet as important a health problem in rural southern India as it is in westernised societies. Those particularly at risk of hypertension, however, are the elderly and overweight people of high socioeconomic class.