The liver is a vital organ necessary for survival, synthesizing crucial molecules including cholesterol, glucose, and fatty acids. Moreover, it makes most plasma proteins including albumin, so its injury or damage leads to disturbance of their blood concentration. Thioacetamide (TAA) established liver fibrosis model with a histopathological appearance that is similar to human cirrhosis however, melatonin considered as one of anti-fibrotic agents through its anti-inflammatory and antioxidant functions, so we aimed to investigate the possible correction role of melatonin on altered serum proteins and liver histopathology on rats with induced liver injury. Sixty male albino rats were classified to equal 4 groups as follows: control, melatonin group (5mg/kg b.w/i.p), TAA group (150 mg/kg b.w/i.p) and TAA + melatonin group after 60 days, the animals were anesthetized to collect blood samples for determination of serum protein concentrations, and liver tissues were collected for histopathological examination. Key finding, liver injury induced by TAA caused marked decrease on serum protein and albumin, this injury was confirmed by histopathological examination that showed interlobular and intralobular cirrhosis associated with severe degree of hepatic vacuolation, On the other hand melatonin successfully improved the serious effects of TAA on liver function through ameliorating the decrease in total protein and albumin concentration along with restoring altered histopathological changes toward normal again. Our study concluded that co-treatment with melatonin may be favorable in protection from hepatic injury caused by TAA.