The subjects of this study were 290 hospital patients who were divided into 4 groups: acute myocardial infarction (100), cardiac ischaemia with angina but no infarction (50), white patients without evidence of coronary heart disease (70), and a group of South African black patients without detectable coronary heart disease (70). Mean serum uric acid (SUA) levels were 8,00 +/- 0,32 in the ischaemic group, 7,09 +/- 0,23 in the acute infarction group, 5,78 +/- 0,21 in normal black patients, and 5,75 +/- 0,21 in normal white controls. The differences in SUA levels between the ischaemic and infarction groups as compared with both control groups was highly significant (p less than 0,001). These differences were most striking in the females aged 60 years and over.