Heart failure in hypertensive patients is known to be dependent not only on the absolute value of blood pressure but also on other factors, hence the prognosis varies. In this study, the effect of renal dysfunction on the development of heart failure in hypertensive patients was assessed. Fifty-five patients who were admitted in hypertensive heart failure (HHF) were compared with 55 hypertensive patients who had never been in heart failure (HT), in their renal function, assessed by serum creatinine and urea levels. The haemoglobin (Hb) and serum albumin (Alb) levels were also measured. The two groups were matched for age, sex, level of blood pressure and body mass index. The duration of hypertension was similar in both groups. Mean serum creatinine was higher in the HHF group: 4.50 +/- 0.90 vs. 0.97 +/- 0.06 mg/100ml (P < 0.001). Also the Hb and Alb levels were lower in the HHF than the HT group: 11.63 +/- 0.40 vs. 13.2 +/- 0.21 g/100 ml (P < 0.001) and 3.7 +/- 0.1 vs. 4.40 +/- 0.09 g/100 ml (P < 0.001), respectively. The proportion with abnormal renal function (creatinine > 1.5 mg%) was also significantly higher in HHF: 28/55 vs. 8/54, chi 2 = 16.3 (P < 0.001). When adjustment was made for low serum albumin, Hb and fundal changes by multivariate analysis, serum creatinine was significantly higher in the HHF group: F = 4.294 (P < 0.05). Low serum albumin was also independent of haemoglobin and creatinine: F = 19.52 (P < 0.001), but Hb was not significantly different after adjustment for Alb and creatinine. This study suggests that renal dysfunction is independently associated with the development of heart failure in HT patients.