To compare the effect of fixed-dose trandolapril-verapamil (FDTV) with that of trandolapril on proteinuria in normotensive, type 2 diabetic patients. A total of 60 normotensive, type 2 diabetic patients with 24-h proteinuria >300 mg were randomly assigned to two groups for open-label treatment. One group received 2 mg trandolapril/180 mg verapamil FDTV once daily; the other group received 2 mg trandolapril once daily. Study drugs were administered for 6 months in both groups. Creatinine clearance and 24-h urinary protein excretion were measured at the beginning and the end of the study. Patients were evaluated monthly for blood pressure, fasting blood glucose level, heart rate, and adverse events. Statistical analysis was performed using ANOVA. Both groups experienced a statistically significant (P < 0.005) mean decrease in mean proteinuria from baseline: FDTV (mean +/- SD 1200 +/- 200 to 540 +/- 79 mg; P < 0.001) and trandolapril (1,105 +/- 212 to 750.9 +/- 134 mg; P < 0.005). A significantly greater reduction from baseline in proteinuria was observed in the FDTV group compared with the trandolapril group. Patients who received trandolapril experienced a statistically significant (P < 0.05) decrease in mean creatinine clearance (91.1 +/- 3.4 to 75.3 +/- 3 ml/min; P < 0.05) compared with patients who received FDTV (88.3 +/- 3.6 to 82.9 +/- 3.5 ml/min; P > 0.05). Final fasting blood glucose was significantly lower in the FDTV group (139 +/- 19) compared with the trandolapril group (154 +/- 22; P < 0.001). No significant differences were observed between the two groups in mean baseline or final measurements of blood pressure, mean heart rate, or frequency of adverse events. Our results suggest that FDTV is more effective than trandolapril in reducing proteinuria in normotensive, type 2 diabetic patients. This effect on proteinuria is not related with blood pressure reduction.