ObjectiveTo study the effects of heroin on Bax expression in the midbrain ventral tegmental area (VTA) of rat. MethodsHeroin was intramuscularly injected into rats and a rat model of addiction was generated. Bax expression in the midbrain ventral tegmental area (VTA) was detected by immunohistochemistry. ResultsThe rats had significant withdrawal symptoms after continuous injection of heroin for 7 days. The expression of Bax-positive cells in cerebellar cortex of rat was significantly increased than that in the control group (P<0.01).ConclusionHeroin has effect of inducing Bax gene expression and damage to brain cells.