Human spermatozoal motility, viability and lipid peroxidation (LPO) have been assessed in Ringer-Tyrode supplemented with different concentrations of ascorbic acid (AA) ranging from 50 to 4000 microM. Ascorbic acid in concentrations below 1000 microM protects spermatozoa from free radical damage as evidenced from improvement in their motility and viability. Concomitantly, there is also witnessed depletion of malondialdehyde generation (an end product of LPO) following AA treatment. Ascorbic acid at 1000 microM concentration and above, however, is not protective, as evidenced by abrupt fall in sperm motility and viability and concomitant increase in LPO.