Eighteen patients with an established angina pectoris aged 46-74 years were investigated. These patients received a low cholesterol, linoleic acid enriched diet during a period of three months. Of these patients seventeen terminated the three months period. The adherence to the diet was assessed by determining the fatty acid pattern in cholesterol and triglycerides. Both were found to increase significantly and to the same extend. When comparing the values between the entry to the study and after three months of dietetic intervention we found a significant improvement in the fibrinogen level, haematocrit, the aggregation of platelets, the PAT I test according to Breddin and in the test according to Wu and Hoak. However, the fibrinolytic activity before occlusion of an arm was disminished. The changes in ADP -, collagen -, adrenalin and thrombin induced platelet aggregation were not uniform. We found a significant lowering of VLDL, LDL, phospholipids and total cholesterol. HDL did not change significantly. It seems that the diet had a favourable effect on several thrombotic and lipoprotein parameters in these patients.