Simvastatin belongs to statins drugs that are used globally for lowering blood cholesterol level in cardiovascular patients. Simvastatin can be considered as life threatening agent, since prolonged usage may cause myotoxicity. Materials & methods: The present study was performed on 20 adult male rats which were divided into: Group I which was the control group that did not receive any treatments, and Group II which was the treated group that received 80 mg/kg b.wt/day of simvastatin for 46 days. All rats were submitted to bone marrow collection for the cytogenetics tests and gastrocnemoius muscles' biopsied were taken for the histochemical tests. Results: statistical analysis showed a non-significant increase in the mean of chromosomal aberrations (CAs) in the treated rats' cells comparing to the control samples. On the other hand, an observed non-significant decrease in the mean of total proteins (TP) content in rats' gastrocnemius muscles of Group II when compared to the control group. Whereas, noticed significant reduction in the mean of glycogen (Glyc.) content in rats' gastrocnemius muscles of the same group when compared to the control group. Conclusion: Simvastatin may lead to an increase in the incidence of (CAs) in bone marrow cells, and determination of TP and Glyc. content in skeletal muscle biopsies can be considered as indicators for muscle necrosis incidence. Recommendations: Simvastatin has to be prescribed carefully in patients suffering from hypercholesterolemia, precautions have to be taken into consideration since it may affect skeletal muscles' health and lead to muscle toxicity on the short or long run of usage.