Unlike previous reports that NK cells function had dichotomy change in cytotoxicity and cytokine secretion [23], [26], [27], our study shown that both the cytotoxicity and secretion of cytokines were decreased, along with the decreased expression of activating receptors of NKp30 and NKG2D in NK cells in patients with chronic hepatitis B. The gene discussed is KLRK1; the disease is chronic hepatitis B virus infection.