Of the 90 naturally occurring elements, 26 are known to be essential to animal life. Eleven of these are regarded as major elements because of their relative abundance in the body: hydrogen, oxygen, nitrogen, sulphur, calcium, phosphorus, potassium, sodium, chlorine, and magnesium. The remaining 15 essential elements are known as 'trace' elements because they are present in animal tissues in such relatively small amounts (microgram per gram) that early workers were unable to measure their concentrations precisely. Trace elements which are essential in various animal species are iron, zinc, copper, manganese, nickel, cobalt, molybdenum, selenium, chromium, iodine, fluorine, tin, silicon, vanadium, and arsenic. Deficiency states in man which are responsive to specific trace element replacement have been described for only iron, copper, zinc, chromium, manganese, and iodine. Cobalt is essential in man as an atom in the vitamin B12 molecule, but cobalt replacement per se will not correct vitamin B12 deficiency states. Perinatologists are concerned with a period of human biology during which trace element nutrition is especially important. The association of maternal dietary iodine deficiency and goiter with congenital hypothyroidism is a long-standing example of the critical role of certain trace elements in fetal development. More recently, symptomatic copper deficient anemia, neutropenia, and osteoporosis have been documented in preterm infants who were born before the late gestational period of rapid fetal copper accumulation. Even infants born at term may become copper deficient if they have been maintained for long periods by total parenteral nutrition without copper supplementation. Maternal zinc deficiency in rats results in congenital malformations which include hydrocephalus, cleft lip and cleft palate. A possible association between maternal zinc deficiency and central nervous system malformations in man has been suggested. Less than optimal zinc intake during infancy has been shown to be growth-limiting in males fed a proprietary formula without zinc supplementation. To bring these examples of the importance of trace elements full circle from fetal development to reproductive capacity, a review such as this can cite zinc deficiency in adolescents, which is associated with growth failure and delayed puberty. While copper and zinc were emerging as important trace minerals in perinatal biology, reports of skeletal demineralization among low-birth-weight infants during this decade served to emphasize that nutritional requirements and metabolism of the major minerals, calcium and phosphorus, are still inadequately understood in the neonate. Moreover, interactions between copper, zinc, and calcium have been found to have important consequences. The article describes perinatal nutritional aspects of the essential trace minerals, except iron, and the interactions of these important nutrients with each other and with calcium.