Serum beta-carotene levels in patients with cardiovascular disease and control subjects were measured. The mean values for beta-carotene were found to be 82.2 +/- 3.5 mug/dl for the cases as a single group, 74.83 +/- 5.6 mug/dl in acute myocardial infarction (AMI) cases, 88.19 +/- 6.1 mug/dl in atherosclerotic cases, 85.11 +/- 6.1 mug/dl in others and 118.2 +/- 4.3 mug/dl in controls. Beta-carotene levels in the cases were significantly lower than in the controls (P<0.05). Serum beta-carotene levels in cases and controls were also compared to take account of age, sex and smoking status. Our data indicate that there are apparent associations between serum beta-carotene levels, sex and smoking status.