Natural killer (NK) cells are key players in the immune response to viruses. This study examined the effect of hepatitis C virus (HCV) on the frequency of NK cells and their subsets in individuals with different clinical outcomes; 20 positive for anti-HCV and HCV-RNA (chronic hepatitis C), 20 positive for anti-HCV but negative for HCV-RNA (spontaneously resolved) and 20 healthy controls free of HCV. There was a significant reduction in the frequency of total NK cells in the chronic group compared to the control (P = 0.001) or resolved (P = 0.01) groups. The percentage of CD56(bright) cells was significantly higher than the control group (P = 0.04). While the percentages of CD56 (dim) cells and their CD16 expression were lower in the chronic group, this was not statistically significant. The frequency of CD3+CD56- T cells was significantly lower in both the chronic and resolved groups compared to the control group (P = 0.04). Our results confirm a potential role of NK cells and the different subsets in the pathogenesis of chronic HCV infection.