The toxic effects of ethanolic camphor leaves extract, Eucalyptus camaldulensis was studied on some biochemical aspects and histopathological studies of white Norway rat, Rattus norvegicus. Results showed that LD₅₀ values was 131.56 mg/kg b.w. Oral administration of sub-lethal  dose (¼ LD₅₀) of tested extract caused significant decrease for the body weight at 24, 48 and 72 hrs after administration. In contrast, there were significant increase for the internal organs weight (liver, kidney, heart, spleen, lung, and intestine) in all cases. Also, the same dose of extract induced a noticeable dysfunction in AST, ALT enzymes, total protein and prothrombin time profile as they significantly increased in plasma after treatment. Also, the effect of ¼ LD₅₀ of ethanolic camphor leaves extract for 24, 48 and 72 hours on liver of R. norvegicus were studied. The microscopical examination showed that there were injuries in liver tissue at 24, 48 and 72 hrs after administration. Generally, ethanolic camphor leaves extract was toxic to rats and exhibited a higher effect on body weight, internal organs, tested enzyme system and liver tissue of rats.