In order to see whether conventional low-dose folic acid supplement along with vitamin B<sub>6</sub> and B<sub>12</sub> reduces hyperhomocysteinemia in patients with ESRD, we compared the levels of homocysteine, vitamin B<sub>6</sub>, B<sub>12</sub> and folic acid among 3 groups of patients: 44 ESRD patients on hemodialysis with replacement of folic acid, vitamin B<sub>6</sub>, and B<sub>12</sub> (dialysis group); 27 chronic renal failure patients without vitamin replacement (predialysis group); and 17 hypertensive patients without vitamin replacement (control group). Mean plasma total homocysteine concentration was higher in the dialysis (15.5 ± 6.6 µmol/l) and the predialysis groups (15.7 ± 4.2 µmol/l) than in the control group (6.2 ± 1.5 µmol/l) (p < 0.001). However, there was no difference in homocysteine concentrations between the dialysis and predialysis groups. In the control and predialysis groups, the homocysteine concentration showed a reverse correlation with the concentrations of folic acid (r = 0.584, p = 0.014 for the control group; r = 0.431, p = 0.247 for the predialysis group) and vitamin B<sub>12</sub> (r = 0.485, p = 0.049 for the control group; r = –0.562, p = 0.023 for the predialysis group) but not with vitamin B<sub>6</sub>. In conclusion, plasma folic acid concentrations were 3–4 times higher in the dialysis than in the predialysis group. But these levels of folic acid are not enough to reduce hyperhomocysteinemia in ESRD.