In a group of 70 probands affected with ischaemic heart disease before the age of 55 years and in their 126 grade I and 8 grade II offspring the ratio of risk factors of the disease was assessed. In the first part of the investigation attention was focused on the frequency of hyperlipoproteinaemias. Elevated total cholesterol and/or triacylglycerols were found in 41% of the probands and 6.4% of the grade I offspring. The most frequently diagnosed type of hyperlipoproteinaemia in probands as well as their offspring was hypertriacylglycerolaemia. Twenty-five per cent of the hyperlipoproteinaemic probands had also a hyperlipoproteinaemic grade I offspring. The author emphasizes that early active screening of offspring of subjects suffering from ischaemic heart disease in young age is essential, in particular those where one of the risk factors is hyperlipoproteinaemia.