The effect of a cholesterol-lowering diet and subsequent fluvastatin treatment (Lescol, Novartis; 20 mg/day) on serum lipids and lipoproteins was investigated in 21 diabetic patients (eight women, 13 men, age range 31-63 years, BMI 25.9 +/- 4.5 kg/m2) who had undergone successful kidney transplantation. A cholesterol-lowering diet followed for 8 weeks had apparently no effect on serum lipid concentrations. Fluvastatin applied afterwards for 12 months significantly decreased the total cholesterol, triglyceride and LDL cholesterol levels from 7.7 +/- 0.94, 2.84 +/- 0.85 and 4.87 +/- 1.05 mmol/l to 6.40 +/- 0.74, 2.64 +/- 0.86 and 3.52 +/- 0.69 mmol/l, P < 0.001, < 0.05 and < 0.001, respectively, while the level of HDL cholesterol increased from 1.12 +/- 0.28 to 1.52 +/- 0.39 mmol/l, P < 0.001. Serum concentration of lipoprotein(a) remained unchanged. The serum level of apolipoprotein-A1 increased from 1.52 +/- 0.28 to 1.83 +/- 0.29 mmol/l (P < 0.01) and that of lipoprotein-B decreased from 1.37 +/- 0.20 to 1.20 +/- 0.36 mmol/l (P < 0.05). These maximum changes were achieved by the 12th week of fluvastatin treatment, and no further significant change was observed in the remaining part of the year. The other parameters that could have influenced lipid metabolism (doses of diuretics and steroid, daily dose and serum level of cyclosporin, kidney function, degree of proteinuria, HbA1c, etc.) remained unchanged throughout the study. Thus, the improvement in lipid concentrations can be ascribed exclusively to fluvastatin. No side effects were observed during the 1-year follow up. Liver enzymes and CPK remained within the normal reference limits. Fluvastatin proved to be an effective and safe drug for treating the dyslipidaemia of transplanted patients receiving steroid cyclosporin immunosuppression.