We have evaluated the incidence, long term evolution and pathogenesis of posttransplant hyperlipidaemia (HL) in 88 transplanted patients without nephrotic syndrome followed for 2 to 13 years by the same staff. Incidence of HL decreased strikingly over the years from 51% at 2 years to 25% at 10 years. This fall was due solely to the return to normal of the lipid profile in 13 patients between 2 and 8 years after transplantation. This progressive decrease should be taken into account when the frequency of posttransplantation dyslipaemia is assessed. The incidence of hyperlipidaemia increases with age. Above 40 years, hyperlipidaemia is more frequent in females than in males. Obesity and reduced renal function are both associated with a higher incidence of dyslipaemia. No relationship was found between lipid disorders and either steroid dosage or fasting blood glucose levels. Dyslipaemia appears thus to be due to the interplay of several factors. Normalisation of the lipid profile occurred in 13 patients without significant decrease in bodyweight, serum creatinine or prednisone dosage. At 8 years atheromatous lesions were not more frequent in dyslipaemic than in normolipaemic subjects.