Bladder cancer is a malignancy greatly affected by behavioral habits. The aim of this study was to examine the effect of opium on changes in the expression of OCT4and SOX2in the bladder tissue of rats. Thirty six rats were divided into six groups: 24 rats in the addicted group received morphine and opium for 4 months with 12 rats in the control group. Blood testing was done for the evaluation of CBC, MDA, and TAC. The bladder tissue was removed and checked by histopathological examination. All total RNA was extracted, then cDNAs were synthesized and the OCT4and SOX2gene expressions were evaluated by Real-time PCR. The OCT4mRNA expression level in the opium group of rats was significantly increased compared to the control group (13.5 and 6.8 fold in males and females respectively). Also, in the morphine group, similar augmentation was detected (3.8 and 6.7 fold in males and females respectively). The SOX2mRNA over-expression level was seen in the morphine group of both genders as compared to the control group (3.7 and 4.2 fold in male and female respectively) but in the opium group, enhancement of mRNA level was seen only in males (6.6 fold). Opium increases both OCT4and SOX2expression more than morphine in male rats, but in female rats, SOX2is increased more by morphine. Over expression of OCT4and SOX2was observed in rats treated with opium and morphine. Increased OCT4and SOX2expression was seen in opium-treated male rats, but in female rats, SOX2was increased more by morphine.