Background: The objective of this study is to evaluate the influence of carbimazole- induced hypothyroidism on the testes of adult albino rats and the probable protective effect of alpha-lipoic acid (ALA). Materials and methods: The rats were divided into four groups; control group, ALA group, carbimazole, and carbimazole + ALA groups. Rats were exposed to ALA (60 mg/kg body weight) or carbimazole (1.35 mg/kg body weight), or both, administered via gavages for 30 days. Results: 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. Additionally, deterioration of the testicular architecture was observed. 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 follicle-stimulating hormone (FSH) in the carbimazole group, indicating reduced steroidogenesis. A significant reduction in reduced glutathione content was detected in the testes of the carbimazole group compared with the controls, while malonaldehyde concentration significantly increased. Conversely, ALA supplementation ameliorated the toxicity induced by hypothyroidism as illustrated by enhanced reproductive organ weights, testosterone, luteinizing hormone, and FSH levels, testicular steroidogenesis, and oxidative stress parameters. Conclusions: 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.