A total of 47 patients suffering from heterozygous hyperlipidemia were treated with LDL-apheresis (24 patients, aged 49.5 +/- 11.5 years), diet and/or lipid-lowering drugs or with diet and lipid-lowering drugs only (23 patients, aged 48.0 +/- 11.9 years). After treatment periods of 44.4 +/- 14.3 (apheresis group) and 33.5 +/- 15.9 (drug group) months, respectively, the ensuing results revealed significant differences (p < 0.0001): total cholesterol decreased from 10.4 to 5.5 vs 9.9 to 8.7 mmol/l, LDL from 7.4 to 3.9 vs 6.6 to 5.2 mmol/l, triglycerides from 5.8 to 3.7 vs 4.8 to 4.1 mmol/l and the LDL/HDL-ratio decreased from 7.1 to 3.4 vs 6.7 to 5.8. In the apheresis group one patient died from myocardial infarction vs one non-fatal myocardial infarction and the manifestation of coronary heart disease in three cases in the drug group. There were no severe side-effects in either group. All patients in the apheresis group experienced an increased clinical performance. On the other hand physological well-being of these patients was lower than that of the drug group (scores 42.3 +/- 8.9 vs 50.2 +/- 9.9, p < 0.002). The present trial suggests that a continuing reduction in serum lipid concentrations may lower in a dose dependent manner the risk of development and progression of coronary heart disease. With respect to clinical and laboratory results, LDL-apheresis seems safe and appears to be the most effective therapy.