In this study, cytoprotective effects of boric acid (BA) and borax (BX) therapy in the rats administered with environmental carcinogens (3-methylcolantren (3-MC) and Benzo(a)pyrene (B(a)P)) were studied. The rats were divided into 9 groups with 12 rats each. Group I was set as control. Group II was administered B(a)P and Group III was administered 3-MC at doses of 100mg/kg intraperitoneally, twice a week, at 4 equal doses. Group IV received only 300 mg/L of BA and Group V was only administered 300 mg/L of BX via drinking water. Group VI received B(a)P + BA, Group VII received 3-MC + BA, Group VIII received B(a)P + BX, and Group IX received 3-MC + BX, and the study was terminated on day 150. In histopathological analysis, hydropic degeneration in liver was seen in the B(a)P group, interstitial pneumonia in lung was seen in the B(a)P + BA group, and hydropic degeneration in liver and interstitial pneumonia in lung were observed in the B(a)P + BX group. Fibrosarcoma occurred in all the groups administered with 3-MC. Fibrosarcoma and diffuse hepatocellular carcinoma developed in the 3 MC group. The administration of BA and BX therapies led to pathological recovery compared to groups administered with B(a)P and 3-MC. This recovery was more prominent in the groups administered with BA therapy. The results of this study indicate that the degree of cytotoxic effect of B(a)P and tumor formations caused by 3-MC may be attenuated by BA and BX therapies.