Vitamin D belongs to the fat-soluble vitamins. Vitamin D deficiency is a common health problem in animals. Vitamin D plays a key role in calcium and phosphate metabolism. Vitamin D deficiency can affect bones health. Pigs synthesize vitamin D3 under exposure to sunlight. Feed is the main source of vitamin D for pigs kept indoors. Vitamin D contents in tissues of suckling piglets depend on maternal vitamin D status before parturition. The aim of this paper was to present important aspects connected with vitamin D in sow and piglet nutrition.