Highly productive lactating cows have much greater needs for minerals and vitamins than low-producing animals. The antioxidant vitamins, vitamin E and β-carotene are beneficial in reducing mastitis. Vitamins (D, E, C and β-carotene) and minerals (Cu, Zn, and Se) are needed for an optimum immune response. Vitamin E is effective in counteracting gossypol toxicity. New research suggests the need for supplemental biotin for dairy cattle. Milk fever is best prevented with anionic diets. There is environmental concern from use of excess P. Grazing lactating cows should have access to high quality free-choice mineral mixtures.