Five groups of winter-housed cows (n = 10 per group) that calved in the winter were used to assess the effect of beta-carotene supplementation on postpartum reproductive performance. Near parturition and immediately after calving the beta-carotene concentrations of the blood plasma were decreased and no differences could be found between the control and the supplemented groups. The results obtained at postpartum day 60 suggest that supplementation of the daily winter ration with 300 mg of synthetic beta-carotene with or without vitamins A, D3 and E exerts the most favourable effect on reproduction, as judged not only from B-carotene and vitamin A contents of the blood plasma, colostrum and milk but also from the improved fertility indices. The number of inseminations per cow was reduced and the conception rate was significantly higher in cows supplied additionally with 300 mg of synthetic beta-carotene with or without vitamins A, D3 and E. It can be concluded that beta-carotene is an important factor in bovine reproduction and that its specific role cannot be taken over by vitamin A.