Recent studies among Indians have shown a high prevalence of hypertension. To determine changing trends in hypertension prevalence, in mean blood pressure (BP) levels and to study urban and rural differences we performed meta-analysis of all available Indian studies. The first such study was reported by Chopra in 1942. Since then many studies (n = 33) in urban and rural areas of India have been performed. In urban populations earlier studies of Dotto (1949), Dubey (1954) and Sathe (1959) showed prevalence of hypertension of 1.24 +/- 0.2, 4.24 +/- 0.4 and 3.03 +/- 0.3% in populations of Calcutta, Kanpur and Bombay respectively. Studies since 1959 used World Health Organisation (WHO) guidelines and have shown increasing trend in hypertension prevalence. Recent studies from Ludhiana (1985) and Jaipur (1995) show that prevalence is 14.08 +/- 1.1 and 10.99 +/- 0.7% respectively. Trend analysis in studies among urban areas (n = 10) shows a significant increase in hypertension prevalence (Mantel-Haenzel chi 2 = 5.99, P = 0.014). Studies in rural areas (n = 14) also show a significant increase in hypertension prevalence (Mantel-Haenzel chi 2 = 5.93, P = 0.014) although the rise is not as sharp as in urban populations (r value, urban = 0.70, rural = 0.67). Changes in mean BP levels were analysed by using mean systolic (S) and diastolic (D) BP in urban men aged 40-49 years from 1959-1995. For SBP there was a significant increase (r = 0.95, P < 0.001) and not with DBP (r = 0.43, P > 0.2). It is concluded that in India hypertension is emerging as a major health problem more so in urban than in rural subjects. The increasing prevalence is related to a rising mean SBP.