The effects of indapamide on diabetic patients with micro-albuminuria were evaluated in a multicentre study to assess the advantages of this compound in long-term renal protection. Thirty-two hypertensive diabetic patients (10 males, 22 females, aged 46-84 years) were given indapamide at 2.5 mg/day for a 2-month period. There was a significant fall in systolic blood pressure (174 +/- 18 to 148 +/- 12 mmHg, P less than 0.001) and diastolic blood pressure (95 +/- 13 to 85 +/- 8 mmHg, P less than 0.001) and in the albumin excretion rate (median, 40.8 to 18.9 mg/l; P less than 0.05). Blood glucose, glycosylated haemoglobin, electrolytes, creatinine and serum lipids remained unchanged. There was a small but significant correlation between changes in systolic blood pressure and changes in albuminuria (r = 0.04, P less than 0.05). Thus, the effect of indapamide on albumin excretion cannot be explained by a decrease in the intraglomerular perfusion pressure alone. Indapamide, therefore, might be of potential interest in the long-term renal protection of the diabetic patient with elevated blood pressure values and/or micro-albuminuria.