1. The oral pharmacokinetics of fluconazole were studied in three groups of volunteers (n = 5) with various degrees of renal function (GFR greater than 70 ml min-1; 20-70 ml min-1; less than 20 ml min-1) and in a group of patients with chronic end-stage renal failure requiring regular haemodialysis. 2. The pharmacokinetics of fluconazole were markedly affected by impaired renal function with the elimination of half-life in Group III (GFR less than 20 ml min-1) being approximately three times that observed in normal volunteers (Group I). 3. Fluconazole renal clearance was positively correlated with GFR. 4. Non-renal clearance of fluconazole decreased with decreasing renal function. 5. Approximately 38% of the 50 mg dose of fluconazole was removed by haemodialysis extending over a 3 h period.