The objective of this research was to verify the effects of dietary alpha-tocopheryl acetate (50 vs. 200 mg/kg diet) and ascorbic acid (0 vs. 1 g/L water) on the relative amounts on semen and motion characteristics, oxidative stability and fertilizing ability of rabbit spermatozoa stored for 24 h at 5 degrees C. A high amount of dietary (alpha-tocopheryl acetate significantly increased the level of Vitamin E in the semen (0.90 vs. 0.41 micromol/L) and its oxidative stability after storage (Thiobarbituric Acid Reactive Substances-- TBARS 15.88 vs. 20.90 nmol Malondialdehyde--MDA/mL). Ascorbic acid showed a different effect in relation to the Vitamin E status of animals: when associated with the higher level of Vitamin E it increased the (alpha-tocopherol and the oxidative stability of semen (2.67 micromol/L and 12.25 nmol MDA/mL, respectively), whereas both parameters were reduced with lower Vitamin E (0.13 micromol/L and 21.20 nmol MDA/mL). Semen traits were not modified by the separate supplementation of supranutritional levels of vitamins, whereas their combination significantly improved the viability and the kinetics of spermatozoa (e.g. track speed: 95.13 vs. 71.31 microm sec(-1)) with an increase in fertility rate (70.0 vs. 63.3; P=0.06) that could be considered almost significant.