It is shown that rHu-EPO and calcitriol treatment and type of dialysis membrane effect total lymphocyte CD4, CD8 lymphocyte counts and CD4.CD8 ratio in hemodialysis patients (HP). The aim of this study was investigate the effect of different factors on these cell populations in hemodialysis patients. 10 healthy individuals and 36 HP were included in this study. Patients were dialysed 4 hours twice or three times weekly with polysulphone membrane. All patients were given calcitriol (0.25 microgram! day), calcium (2 gram/day) and other medications as required. Blood samples were taken before each dialysis session. Total lymphocytes count was performed using Technicon HI 873. CD4, CD8 lymphocytes was meusared by IF A. Data were analysed by minitab computer statistic programs (t test, correlation tests). Total lymphocytes, CD4, CD8 lymphocytes and CD4, CD8 lymphocytes and CD4: CD8 ratio of IIP were those of the control group. There was no correlation between total lymphocytes, CD4, CD8 lymphocytes, CD4.CD8 ratio and age, sex, use of rHu-EPO, weight, liver function, time on dialysis and DIIEA-S in HP. Total lymphocytes, CD4, CD8 lymphocytes and CD4.CD8 ratios were high in HP with serum creatinine levels lower than 7 mg/dl. Although this increase was not significant. Increase in CD8 and decrease in CD4.CD8 ratio were significant in anti HCVpositive HP.