In order to assess the interrelationships between the lipemic and the haemostatic balance the Authors studied the behaviour of some thrombotic markers in hyperlipemic subjects. The series consists of 35 subjects (15 m, 20 f, mean age 56 +/- 9 years) suffering from primary polygenic hyperlipoproteinemia of type IIA (23 cases) and type IV (12 cases) (cholesterol and triglyceride values exceeding respectively 250 and 180 mg%); 38 control subjects matched for sex, age and body weight were also examined; all the subjects were without hepato-renal and endocrine-metabolic disorders as well as without clinical signs of arteriosclerotic vasculopathy. For each subject the Authors performed the assay of the fasting plasma levels of total cholesterol (TC), triglycerides (TG) (enzymatic methods), fibrinogen (F) (coagulometric method), factor VII (coagulometric method) (F VII), antithrombin III (AT III) (chromogenic method), tissue activator of plasminogen (tPA), beta-thromboglobulin (BTG) and D-dimer (D-D) (ELISA method). The type IIA hypercholesterolemic subjects showed a not significant trend in a thrombophilic sense of the markers (increase of F, F VII, BTG and D-D, decrease of AT III); the type IV hypertriglyceridemic subjects exhibited a significant (0.05) increase of factor VII, BTG and D-D compared to the control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)