Background: Asthenozoospermia is one of the most prevalent causes of male infertility. Although cryopreservation is an in- dispensable part of assisted reproductive centers, it decreases sperm quality. Adding an antioxidant to the cryopreservation medium could be an effective strategy to decrease the adverse effects of cryopreservation. Alpha lipoic acid (ALA) has been described as a potent biological antioxidant. In this study, the effect of ALA supplementation on sperm parameters during cryopreservation of semen samples of asthenozoospermic men was assessed. Materials and Methods: Thirty semen samples were col- lected from asthenozoospermic patients who had been referred to the infertility treatment center of Qom University Jihad in 2021. Each sample was divided into 3 groups: Control (fresh), Freeze (treated with cryo-protectant alone), and Freeze+ ALA (treated with cryo-protectant+ 0.5mM ALA solution [8-10]). In the freezing groups, samples were cryopreserved with hu- man sperm freezing medium and rapid freezing method. In each sample, sperm mobility according to WHO criteria, sperm viability using eosin-nigrosin staining and sperm morphology using the Diff Quick kit were assessed. Data were analyzed statistically using the Repeated Measure Analysis method and Bonferroni post-hoc test. Results: Sperm motility, viability and normal morphology sig- nificantly decreased in the Freeze group compared to the Con- trol group (P=0.000). Whereas, in the Freeze+ ALA group a significant increase was observed in these parameters compared to the Freeze group (P=0.000). Conclusion: Our results showed that ALA ameliorates the ad- verse effects of cryopreservation on sperm quality in astheno- zoospermic men.