Transplantation of pancreatic gland with systemic venous drainage of the graft causes elevated plasma levels of insulin. To examine lipid metabolism triglyceride clearance capacity, lipolytic enzymes, plasma lipids and lipoproteins were quantified in pancreas-kidney transplant recipients and compared them to lipid parameters of healthy controls and those of patients who had received only kidney transplants. Eleven pancreas-kidney transplant recipients with type I diabetes, 9 non-diabetic kidney transplant recipients as controls for the effects of immunosuppressive medication, and 11 healthy controls were studied. In pancreas-kidney transplant recipients fasting cholesterol, non-HDL cholesterol, triglyceride levels were found 5.5 (+/- 1.0), 3.4 (+/- 0.78) and 1.06 (+/- 0.29) respectively and expressed in mmol/L (mean +/- SE). The results were statistically not different from those of healthy controls. In contrast, non-diabetic kidney transplant recipients cholesterol, non-HDL cholesterol and triglyceride levels were increased to 6.1 (+/- 0.81) (p < 0.05), 4.6 (+/- 1.1) (p < 0.05) and 2.34 (+/- 1.53) mmol/L (p < 0.05). HDL cholesterol averaged 2.08 (+/- 0.36) in pancreas-kidney transplant recipients, clearly higher than that of kidney transplant recipients 1.53 (+/- 0.39) mmol/L (p > 0.01), or of controls 1.61 (+/- 0.37) mmol/L (p < 0.05). In pancreas-kidney transplant recipients postprandial lipaemia was the lowest and lipase activity was the highest compared both to kidney transplant recipients (p < 0.001, p < 0.05) and controls (p < 0.01, p < 0.05). This excellent triglyceride clearing capacity appears to be the result of a high activity of lipoprotein lipase, which, can be explained by the peripheral hyperinsulinaemia.