The current study covers key issues related to memantine's toxicity (0.36 mg/kg, P.O. once daily) and its effect on liver, Kidney, blood and antioxidant enzymes for three weeks. Then tissue and blood samples were collected at the 1st, 2nd and 3rd weeks post-treatment. Our results indicated that Memantine has hepato-nephrotoxicity and elevation of liver enzymes (ALT, AST and ALP), creatinine, urea and uric acid. Obvious decline in all blood parameters with respectable decline in antioxidant enzyme like CAT, SOD, GPX and a significant increase in MDA. Histopathology revealed hepatic steatosis and increase the apoptotic and necrotic cells mostly within the centrolobular, as. Also, tubular basophilia and interstitial nephritis were observed. Therefore, Memantine should be used with caution with hepatic or people with kidney problems.