The nature of vascular disease and its complications are different in juvenile-onset (JOD) and maturity-onset (MOD) diabetes mellitus. In order to explore the disturbances in the coagulation-fibrinolytic system, platelet adhesiveness, plasma fibrinogen, and euglobulin lysis time were estimated in 26 cases of MOD. Two groups of age- and sex-matched controls were also studied. Platelet adhesiveness and plasma fibrinogen were essentially normal while euglobulin lysis time was significantly decreased in the JOD group. The MOD group, on the other hand, showed a reversed pattern in the form of enhanced platelet adhesiveness and plasma fibrinogen and no compensatory increase in fibrinolysis.