The plasma β-carotene status of non lactating Holstein-Friesian cows in a commercial dairy was found to be deficient (mean 1.2 μg /ml). Subsequently three experiments were conducted to evaluate the influence of 300 and 500 mgβ-carotene supplementation per cow per day commencing 21 days prior to expected calving date and continuing for 70 days after calving on reproductive performance and periparturient health. There were considerable fluctuations in plasma β-carotene concentrations in cows around the time of calving in both supplemented and unsupplemented animals. However plasma concentrations tended to decrease as calving approached and where at their lowest 10 days after calving. β-carotene supplements significantly decreased the incidence of retained placenta, mastitis and reduced the days from calving to first heat.