Background: Hypothyroidism is a metabolic disorder affecting the functions of many tissues in the body including the testis. It acts via creating an oxidative stress and decreasing the antioxidant capabilities. Testis is rich in the polyunsaturated fatty acids content and lacks strong intrinsic antioxidant system making it prone to such oxidativde stress. L-carnitine (LC) regulates long chain fatty acids metabolism; and is considered a valuable antioxidant factor. Aim: To evaluate the effect of hypothyroidism induced by propylthiouracil (PTU) on rat’s testes with the possible protective role of LC. Methods: Forty-eight adult male albino rats have been used in this work. The animals were divided into three groups with sixteen animals in each. Group 1 (Control): Animals were kept without medications. Group 2 (PTU-treated): was subjected to administration of PTU; while group 3 (PTU and LC) received both PTU and LC. By the end of the experiment “30 days”, blood samples were taken for hormonal essay then animals were anaesthetized and sacrificed. Specimens were homogenized for biochemical analysis; epididymal content of each rat was obtained immediately for semen analysis. Testes’ specimens were harvested, prepared and examined by light microscope examination. Results: Induced hypothyroidism was noticed to cause histopathological, morphometric and biochemical changes in rat’s testes. LC protected the testicular specimens against such changes; it also improved the seminal quality and quantity as well as testicular structure and biochemistry. Conclusion: Hypothyroidism could result in hazards to the structure of testis. Fortunately co-administration of LC is suggested to reduce such hazards