Tramadol, a centrally acting analgesic opioid, is considered to have a low abuse potential and is devoid of side effects likedrug dependence, liver and kidney toxicity.. The present study was conducted to assess the tramadol addiction effects onboth liver and kidney functions among tramadol abusers. A total of 50 male individuals with a tramadol abuse problemwere referred to psychiatric clinics in Gaza Strip, along with an age matched normal control. An informed consent wasobtained, a questionnaire was filled, blood samples were collected, serum was separated, and tested serologically to detectantibodies to hepatitis A virus, the presence of hepatitis B surface antigen, and IgM antibodies to hepatitis A virus.Aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase(LDH) activities, bilirubin, creatinine, uric acid and blood urea nitrogen (BUN) levels were measured in the serum. SerumALT, AST and LDH levels were significantly higher in abuser group compared to the control group. Serum ALP, directbilirubin, total bilirubin, BUN, uric acid and creatinine levels significantly increased in the abusers that were addicted totramadol for more than 5 years. Our results point out the risk of increased hepatic and renal damage due to a long-term useof tramadol. Although opioids are reported to be effective in pain management, their toxic effects should be kept in mindduring the chronic usage. In addition, measures to control the spread of tramadol abuse should be implemented.