Excessive generation of reactive oxygen species and increased peroxidation of the phospholipids in the membrane is proposed as a biochemical basis for the reduced activity of spermatozoa in cryopreserved semen. The possible role of alpha-tocopherol (VE) and ascorbic acid (VC) in improving the quality of frozen semen was investigated. Semen samples were divided into aliquots and frozen in freezing media with and without VC or VE. Sperm parameters, including motility after thawing and also at 2 h, % grade A motility (rapid and linear forward progression), and hypoosmotic swelling (HOS) scores, were measured in all samples. Vitamin C did not result in any improvement in sperm parameters studies. Vitamin E improved the post-thaw motility minimally. This improvement, although statistically significant, was actually very small. There were, however, wide variations between the samples. The motility improvement was considered in 5 of 12 samples, and HOS improved in some of the samples tested with VE. Future studies are needed to determine if these antioxidants can produce a consistent improvement in some individuals rather than help the majority of patients.