To determine the impact of long-term immunosuppression on serum lipids in stable renal graft recipients we measured serum lipids and apolipoprotein B concentrations in 20 patients receiving therapy with cyclosporin (CsA) and low-dose prednisolone (CsA/P) and in 18 patients on therapy with azathioprine and maintenance steroids (Aza/P). The patients were matched for age, body mass index, primary renal disease and dose of prednisolone, but not for the duration in transplantation and serum creatinine concentration. Triglyceride concentrations were significantly higher in the CsA/P group than in Aza/P-treated patients: 2.62 +/- 0.35 vs 1.62 +/- 0.23 mmol/l (P less than 0.05). Similarly, total cholesterol (C) levels were significantly more elevated in the CsA/P recipients than in the other group: 7.44 +/- 0.32 vs 5.84 +/- 0.25 (P less than 0.02). CsA/P patients had higher serum levels of LDL-C (4.79 +/- 0.20 vs 3.43 +/- 0.19 mmol/l (P less than 0.001) and apolipoprotein B concentrations (191 +/- 13 vs 128 +/- 9 mg/dl: P less than 0.001). CsA/P and Aza/P recipients had similar concentrations of HDL-C (1.73 +/- 0.13 vs 1.52 +/- 0.09 mmol/l: NS). We conclude that in stable renal graft recipients with good transplant function long-term immunosuppression with CsA/P is associated with a more atherogenic lipid status than therapy with Aza/P.