We studied serum lipids and post-heparin triglyceride lipase activities in 8 patients with Beta-Thalassaemia Major, under high transfusion programme and regular chelation therapy and in 8 control subjects. Total cholesterol and HDL-cholesterol were significantly lower in patients with Cooley's anaemia, whereas triglyceride levels did not differ in the two groups. Post-heparin triglyceride lipase activities were determined according with the method of Krauss et A1. using glyceryl-tri-(1-14C)oleate as substrate and NaCl to inactivate the extrahepatic lipase. These enzymatic activities (both hepatic and extrahepatic) resulted significantly lower in thalassaemic patients. We suppose that the decreased levels of these enzymatic activities could play a role in determining the decrease of HDL-cholesterol that we observed in our thalassaemic patients.