Backgrounds: The researches on endocrinopathy related with oral opioids had focused more on males, while fewer studies had focused on females. Objective: it was to demonstrate the possible chronic tramadol toxic effect (histopathological & biochemical) on ovary and endometrium of adult female albino rats. Materials and methods: Twenty-five female rats (control group), were given normal food and water, while one hundred adult female rats were given 30 mg/kg/day tramadol dissolved in distilled water (which represent 1/10 LD50) on daily basis for each rat for 3 months (An average 0.6ml for each rat). Rats were weighted at the beginning of the study and then 2 times weekly. At end of this period, blood samples were taken for Biochemical analysis. Rats' ovaries and uterus were examined by light microscope after staining with Haematoxylin and Eosin, and then data were analyzed and statistically studied. Results: Our study showed gradual decrease in female body weight and levels of sex hormones. In tramadol treated group, ovaries showed apparent decrease in the number of growing follicles and an increase in the number of corpora lutea. The medulla showed dilated congested blood vessels. Many of the follicles appeared atretic. In the corpora lutea, there were degenerated cells. While endometrium in tramadol treated group there was apparent atrophic glands and stroma in the surface of the endometrium with appearance of inflammatory cells in the stroma. Conclusion: it has harmful histopathological and functional effects on the reproductive organs of female albino rats.