Abstract: The objective of this study is to evaluate the influence of carbimazole-induced hypothyroidism on testis of adult albino rats and the probable protective effect of α-lipoic acid (ALA). The rats were divided into four groups; Control, α-lipoic acid group, carbimazole, and carbimazole+α-lipoic acid groups. Rats were exposed to ALA (60 mg/kg BW) or carbimazole (1.35 mg/kg BW) or both via gavages for 30 days. Morphometric analysis revealed a significant decrease in tubular diameter, germinal epithelium thickness, and interstitial space as compared to the controls. Also, rats exposed to carbimazole showed a significant decline in testicular weight, sperm motility, and count. Also, deterioration of the testicular architecture. ALA supplementation resulted in a significant improvement in the tubular diameter and germinal epithelium thickness, but no significant improvement regarding interstitial space was observed. Another observation was the significant decline in serum testosterone and FSH in the carbimazole group, indicating reduced steroidogenesis. A significant reduction in reduced glutathione content was detected in the testes of the carbimazole group over the controls, while malonaldehyde (MDA) concentration significantly increased. Conversely, ALA supplementation ameliorated the toxicity induced by hypothyroidism as illustrated by enhanced reproductive organ weights, testosterone, LH, and FSH levels, testicular steroidogenesis, and oxidative stress parameters. Hypothyroidism altered testicular antioxidant balance and negatively affected spermatogenesis. On the other hand, ALA through its antioxidant properties alleviated testicular toxicity in carbimazole-exposed rats.