Abstract: Objective To investigate the effects of interferon-γ (IFN-γ) on proliferation,cell cycle,apoptosis and invasion of mouse leukemia cell line FBL-3. Methods The leukemia cellular proliferation capacity was determined with MTT assay,cell cycle distribution and apoptotic rate were measured with flow cytometry and the invasion capacity was assayed in a Transwell cell culture chamber.Result（1）Low dose of IFN-γ (5 ng/ml) had no significant effects on proliferation of FBL-3 (P＞0.05).The survival rate of FBL-3 stayed up to about 80% after treated by IFN-γ (50~200 ng/ml) for 48 h while higher dose of IFN-γ (500 ng/ml) had significant suppressive effects (less than 50%) (P＜0.05)；（2）The FBL-3 cell number at G0/G1 phase was increased and cell number at G₂/M phase was relatively reduced after treatment,indicating that cells were arrested at G₀/G₁ phase by IFN-γ；（3）IFN-γ had promotive effects on apoptosis and suppressive effects on cell invasion capacity of FBL-3 cells in a dose-dependent manner (P＜0.05). Conclusion IFN-γ had definite effects against leukemia through suppressing proliferation,promoting apoptosis and decreasing cell invasion directly in a dose-dependent manner.