Ten children on total parenteral nutrition were studied. Plasma copper, zinc, manganese and selenium levels were determined by neutron activation and gamma spectrometry, every 10 days. With a copper intake of 20 microgram/kg/24 h, the average level 120 microgram% (94-144) was normal (N: 118 microgram +/- 11%). With a manganese intake of 40 microgram/kg/24 h, the level increased to 2.6 microgram% (1.3-4.5) (N: 1.1 microgram +/- 0.2%). With a zinc intake of 30 microgram/kg/24 h, the level decreased to 45.9 microgram % (20-63) (N: 83 microgram +/- 28%); with an intake of 50 microgram/kg/24 h the level remained under normal. With a selenium intake of 1 microgram/kg/24 h, the level decreased to 10.6 ng/ml (3.6-21.6) (N: 38.2 ng/ml +/- 11.9), but was normalized with an intake of 3 microgram/kg/24 h. From these results, with all reserves that estimation implies, the authors suggest that the disorders due to deficit or excess of trace elements could be avoided by daily intakes per kg of body weight: copper 20 microgram, zinc 100 microgram, manganese 10 microgram and selenium 3 microgram, with supplementation of iron, iodine and fluoride.