Dialysis adequacy (Kt/V) was investigated in two groups of patients on continuous ambulatory peritoneal dialysis (CAPD). Group I consisted of patients with serum creatinine concentration above 1200 mumol/l and Group II comprised patients with serum creatinine concentration of 600 mumol/l and less. The mean Kt/V was significantly higher in Group II (Kt/V, 2.0) than in Group I (Kt/V, 1.59; p < 0.01) patients. The mean duration of CAPD was significantly longer in Group I (3.12 years) than in Group II (1.32 years; (p < 0.01) patients, and the mean total creatinine clearance for Group II patients was significantly higher than for Group I (p < 0.001) patients. There was good correlation between Kt/V and total creatinine clearance (r = 0.73; p < 0.001); and between Kt/V and normalized protein catabolic rate (NPCR, r = 0.6; p < 0.001). There was weak correlation between Kt/V and duration on dialysis, but this was statistically significant. There was no significant difference between mean NPCR and mean mid-arm muscle circumference (MAMC) in the two groups and no significant association between Kt/V and dietary inventory. Group II patients had a significantly better residual renal clearance (p < 0.0001). Pruritus was a troublesome feature in Group I patients but in both groups patients were distressed by loss of libido, insomnia and tiredness. This study revealed that Group II patients with lower creatinine concentrations had better dialysis adequacy but were on CAPD for a shorter duration than Group I and had significantly better residual renal clearance and total clearance. Muscle mass does not appear to have contributed significantly to the differences in creatinine concentration between the groups. Additional studies on peritoneal membrane function vis-à-vis solute transfer are in progress.