Colostrum is the first natural food produced by female mammals during the first 24–36h directly after giving birth. Chemically, colostrum is a very complex fluid rich in nutrients, antibodies and growth factors. In cows the antibodies provide passive immunity to the new born calf, whereas the growth factors especially stimulate the growth of the gut. The other antimicrobial components of colostrum include lactoferrin, lysozyme and lactoperoxidase. Bovine colostrum has also been used as a raw material for immunonoglubulin-rich commercial products (immune milk preparations). These products can be given orally to patients who are suffering infections of the gastrointestial tract or in order to prevent these infections. Usually, however, the cows have to be hyperimmunized against microorganisms, if specific antibodies are required. Several animal studies have shown that the growth factors in bovine colostrum, especially insulin-like growth factors, stimulate cell growth in the gut. Bovine colostrum is also known to contain insulin, transforming growth factor β and related growth factors, but their function in colostrum is not fully understood. Small amounts of these growth factors can also be detected in normal milk. Growth factors as well as antimicrobial factors of colostrum may be used as potential components in clinical nutrition in the future.