Thyroid functions were evaluated in 85 patients with end-stage renal failure, 44 treated by hemodialysis (HD) and 41 by con-tinuous ambulatory peritoneal dialysis(CAPD) and compared with 18 healthy subjects. Serum total triiodothyronine (TT3) were low in both HD and CAPD groups (p<0.001 and p< 0.015 respectively). Serum free thyroxine (fT4) concentration was low in HD (p<0.027) and free triiodothyronine (fT3) was low in the CAPD group (p<0.01) with respect to normal. There was no striking difference between the two study groups' serum total thyroxine (TT4), TT3, fT4, fT3 and thyroid stimulating hor-mone (TSH) levels.