In this study, the effects of heroin on the embryo of addicted mice were determined. For this purpose, the parents were addicted with gradual increase in concentration of heroin (0.1, 0.3 and 0.5 mg/ml, in drinking water). The female and male mices were categorized in 5 groups: females as prepregnant addicts, post pregnant addicts and pre and post pregnant addicts and males in healthy and addicted groups. On the 17th day of pregnancy, it was found that the decrease in embryo’s weight and crown rump length, were significant. Also we reconfirmed that crown rump length, absence, or decrease of gametogenesis and decrease of sexual activities, prolonged fertilization period, embryo and parental death, and also abnormalities in different tissues (digital process., diversion of body axis, growth stunting, subcutaneus hemorrhagia, tail diversion, opened eyelids, abnormal flextures, in vertebral column, etc).