Calcium (Ca) and phosphorus (P) absorption depends on vitamin D. Vitamin deficiency in children results in rickets and osteoporosis in adults. Prematurely born infants are at risk of osteopenia and rickets. Skin synthesis of vitamin D can obtain the level of 10 000 IU (250 ug) when the whole body is exposed to the sun. Recent opinion on vitamin D requirement establishes the level of more than 80 nmol/L of 25(OH)D. There are no recommendations for children but it seems that due to the risk of skin cancer, exposure to the sun in children will be limited and as a result higher dose of vitamin D will be needed. Calcium and phosphorus are the most common minerals of the human body. Calcium concentration in human milk is not related to the intake. Calcium intake of calcium in premature infants is 70-140 mg/100 kcal. Phosphorus content in breast milk, even as low as 15 mg%, can maintain the optimal Ca/P ratio of 2/1. Prolonged breast feeding without additional Ca and P, may result in reduced bone mineralisation. Higher content of calcium in infant formula in comparison to human milk is due to the fact that Ca absorption from breast milk is 60% in comparison to 40% absorption from the formula.