Some cytokines [interleukin (IL) - 1 , IL-2, IL-6, IL-8, IL-10, IL-12, Tumor Necrosis Factor alfa (TNF - α)] are effective on liver function of healthy and sick individuals. The purpose of this study was to determine cytokine activity in patients with Hepatitis C Virus (HCV) infection. The levels of IL - 1 , IL 2R, IL 6, IL 8 and TNF- α in patients with hepatitis C were determined with chemiluminance method. Ten healthy volunteers were selected as controls (Group I), 10 patients with acute hepatitis C (Group II), 10 patients with chronic hepatitis C (Group III), and 10 patients with chronic hepatitis C who received six months of INF therapy (9 million U/week) (Group IV). In Groups I, III, and IV; IL I Β was on undetectable level. In Group II, IL- 1Β was 9.82 ± 0.11 pg/ml, and there was significant difference between group II and the others. IL-2R levels in Groups I, II, and IV were between 515.9 ± 23.35 and 563.05 ± 5.22 U/ml. In Group III, IL-2R was 775.85 ± 7.98 U/ml. In Groups I, II, III; IL-6 < 5 pg/ml; in Group IV IL-6 was 6.84 ± 0.22 pg/ml. IL-6 was 5.05 pg/ml in Group IV. TNF-αwas 5.75 ± 0.36 pg/ml in Group I, and in groups II, III, IV it was between 10.49± 0.5 and 16.76 ± 0.12 pg/ml. As a result, IL-1Β was found higher in acute HCV infection, IL-2R and IL-8 were higher in patients with untreated chronic HCV infection. IL-6 was higher in chronic HCV patients treated with interferon. TNF-α was found higher in all groups except in the control group. Futures studies can enlighten the effect of cytokines on chronic hepatitis C infection and its therapy.