A total of 166 patients who had one or more attacks of myocardial infarction and those with angina pectoris, forty-five relative of 18 hyperlipidemic survivors of ischaemic heart disease, and 330 healthy persons (controls) were investigated for serum lipid profiles. Fifty-six of the 166 patients were hyperlipidemic. The commonest abnormalities in lipoproteins were Types IIa, IIb and IV. 75.5% of the 45 relatives investigated were hyperlipidemic. The familial studies showed that hyperlipidemias occurred in the family members of persons with ischaemic heart disease suggesting that hyperlipidemia could play an important role in predisposing familial clustering of coronary heart disease. A family history of heart disease may be a useful marker for identifying persons who are more likely to have high levels of blood lipids for possible treatment.