Objective To investigate the effect of berbamine (BBM) on the proliferation and apoptosis of retinoblastoma (RB) HXO-RB44 cells and its possible mechanism in vitro.Methods RB cells in logarithmic growth phase were divided into BBM treated group and control group. RB cells in BBM treated group were cultured with different concentrations of BBM (2,4,8,16 and 32 mg/L) for 24,48 and 72 hours, respectively. The proliferation was assayed by methyl Thiazolyl tetrazolium (MTT). RB cells were cultured with different concentrations of BBM (4,8 and 16 mg/L) for 24 hours. The early apoptotic rates were detected by flow cytometry; the expression of bcl-2 and Bax were measured by enzyme-linked immunosorbent assay (ELISA) and the activity of Caspase-3 was detected by colorimetric assay.Results BBM could obviously inhibit the proliferation of RB cells in a time and dose dependent manner (24 hours: F=70.547,P＜0.01; 48 hours: F=603.438,P＜0.01; 72 hours: F=577.521,P＜0.01). The IC50 value at 24,48 and 72 hours were 25.26, 10.94 and 6.25 mg/L, respectively. Necrosis rates of control group and BBM treated group were (1.25plusmn;0.45)%, (4.10plusmn;2.95)%, (4.39plusmn;0.21)% and (10.54plusmn;4.38)% respectively; the difference between two groups was statistically significant (F=6.527,P＜0.05). Apoptotic and necrosis rates in advanced stage of control group and BBM treated group were (2.13plusmn;0.71)%, (5.45plusmn;2.31)%, (9.86plusmn;3.18)% and (11.10plusmn;1.70)%, respectively. The difference between two groups was statistically significant (F=10.845,P＜0.05). Early apoptotic rates of control group and BBM treated group were (0.51plusmn;0.26)%, (2.68plusmn;0.35)%, (5.97plusmn;0.50)% and (11.22plusmn;1.17)%, respectively. The difference between two groups was statistically significant (F=144.976,P＜0.01). In addition, BBM dose-dependently reduced bcl-2 level and increased Bax expression, causing the reduction of the bcl-2/Bax protein ratio as well as increased the Caspase-3 activity in RB cells remarkably (bcl-2: F=835.726,P＜0.01; bax: F=111.963, P＜0.01;Caspase-3:F=298.058,P＜0.01).Conclusions BBM can inhibit the proliferation and induce apoptosis or necrosis of RB cells in vitro, down regulating the expression of bcl-2, up regulating the expression of Bax. Along with increased Caspase-3 activity these may be the apoptotic mechanisms.