The efficacy, safety, and pharmacokinetics of carvedilol were investigated in an open trial performed on six patients with hypertension and chronic renal failure requiring hemodialysis. The plasma level of unchanged carvedilol after a single dose of 10 mg reached a peak 1-5 h after administration both on days with and without hemodialysis. The drug was gradually metabolized thereafter and had almost disappeared from the plasma after 24 h. Blood pressure was lowered by carvedilol both on days with and without hemodialysis. No carvedilol passed through the dialysis membrane. During the 4-week administration period of carvedilol at 10 mg/day, assessment of plasma samples taken just prior to early morning administration demonstrated no drug accumulation. Blood pressure was well controlled during the administration period. Tolerance to the antihypertensive effect was not observed. Heart rate was not significantly changed at any time. There were no side effects in any of the patients during the trial, and laboratory parameters remained unchanged. These results indicate that carvedilol is a safe and effective antihypertensive agent for use in patients on chronic hemodialysis.