To determine prevalence of various lifestyle coronary risk factors and their association with coronary heart disease (CHD) prevalence we studied 3397 Indian men (1982 rural, 1415 urban). A doctor-administered questionnaire, physical examination and electrocardiography was used. CHD was diagnosed by clinical history and electrocardiographic criteria. Lifestyle risk factor prevalence was: illiteracy 1238 (36%), nuclear family 575 (17%), crowded housing (> or = 3 persons/room) 837 (25%), > or = 4 children 881 (26%), smoking 1554 (46%), alcohol intake 592 (17%), non-vegeterian diet intake 835 (25%), high fat intake 1196 (35%), absence of prayer habit 2276 (67%), absent leisure-time physical activity 2832 (83%) and obesity (body-mass index > or = 27 Kg/M2) 265 (8%). In rural as compared to urban men there was a significantly higher prevalence of illiteracy (39% vs 33%), crowded housing (30% vs 17%), smoking (51% vs 39%), alcohol intake (19% vs 15%) and high fat intake (39% vs 29%) (p < 0.01). In urban as compared to rural men the prevalence of nuclear family (28% vs 9%), > or = 4 children (29% vs 24%), non-vegetarian diet intake (35% vs 17%) and sedentary lifestyle (86% vs 81%) was more. CHD prevalence was seen in 152 (4.5%). The prevalence of CHD was significantly more in urban men (urban 6.0% vs rural 3.4%, p < 0.001). Odds ratios (95% confidence intervals) for CHD and lifestyle risk factors showed significant positive associations with nuclear family 1.61 (1.15-2.24), > or = 4 children 2.10 (1.51-2.93), crowded housing 1.48 (1.04-2.10), sedentary lifestyle 1.47 (1.00-2.25) and smoking 1.30 (1.00-1.80), and inverse association with high fat intake 0.42 (0.28-0.63), and not with illiteracy 0.99 (0.70-1.39), alcohol intake 0.84 (0.53-1.32), non-vegeterian diet 0.89 (0.61-1.29), absent prayer habit 1.26 (0.88-1.81), or obesity 1.42 (0.83-1.32).