Pineapple fruit (Ananas comosus) can inhibit the activity of cytochrome 2E1 (CYP2E1). Isoniazid (INH) is one of the most important antituberculosis drugs and it undergoes hydrolysis in the liver via an enzymatic reaction with CYP2E1, resulting in the formation of hepatotoxic compounds. Extracts of ethanol and water from pineapple fruit can decrease alanine transaminase (ALT) and aspartate transaminase (AST) levels in rats, the increased ALT and AST levels are directly proportional to the damage of liver function. The aim of this study was to evaluate the hepatoprotective activity of pineapple juice in INH-induced rats. Materials and Methods: Rats were divided into four groups. The normal group (Group 1) was treated with water, the negative group (Group 2) was induced with INH, the positive group (Group 3) was treated with silymarin and the test group (Group 4) was treated with pineapple juice. The treatments for all groups were administered orally for 8 weeks. Rat blood was collected at 0, 2, 4 and 8 weeks after the start of treatment. Levels of ALT and AST were determined using the photometric method and the rat livers were taken for histopathological testing during week 8. Data were analyzed using the one-way analysis of variance test with a 95% confidence interval. Results: Based on the data analysis, pineapple juice exhibited hepatoprotective activity, as it decreased the ALT and AST levels in the rats after 4 weeks of treatment. Conclusion: Pineapple juice, protected the rats’ livers by inhibiting the central venous diameter widening, although the data analysis showed that the liver function in these rats was not as good as that in the positive controls.