The pharmacokinetics of amlodipine was studied in 27 subjects with renal function ranging from normal to dialysis-dependent. Amlodipine (as a single 5-mg capsule) was administered once daily for 14 days and its plasma concentrations were measured by gas chromatography during and after treatment. Renal impairment had little or no effect on the pharmacokinetics of amlodipine. The elimination half-life was of the order of 50 h, similar to previously observed values, and did not vary with differences in renal function. Steady-state predose concentrations were observed after the ninth dose. Accumulation of amlodipine to steady-state levels was not significantly different from that expected on theoretical grounds and did not significantly change with renal function. These results suggest that once-daily administration of amlodipine is suitable for all degrees of renal function and that dosage adjustment is not necessary in renal impairment.