Abstract: Disclosed is a method for preparing activated lymphocytes, which comprises isolating lymphocytes from peripheral blood and proliferating and activating the isolated lymphocytes in vitro. According to the disclosed method, highly effective toxic cells can be prepared in large amounts by culturing human peripheral lymphocytes in the presence of an anti-CD3 antibody, IFN-? and IL-2. The activated lymphocytes proliferated according to the disclosed preparation method comprise both CD3-CD56+ (natural killer cell marker) cells that are the main components of LAK cells, and CD3+CD56+ cells that are the main components of CIK cells, and can be cultured in large amounts. Thus, the lymphocyte cells can show a significantly higher anticancer effect compared to when the LAK cells and the CIK cells are used alone.