Administration of home parenteral nutrition (HPN) to patients with intestinal failure requires attention to caloric content of feeds, fluid, electrolyte balance, and micronutrient status. Peripheral blood estimations of vitamins and trace elements may be abnormal, but their clinical significance in relation to deficiency or toxicity states is not always clear. We sought to determine the incidence and nature of clinical micronutrient abnormality in our HPN program. Clinical assessment and case record review of 49 patients actively receiving HPN was undertaken, and, in 32 of these patients, serum micronutrient levels were assayed. Clinical evidence of micronutrient deficiency was identified in 16 patients (33%). Iron deficiency anemia occurred in 14 patients which resolved after iron supplementation in all except 1 patient who had persistent intestinal blood loss. Anemia was precipitated in six patients by identifiable clinical events (acute gastrointestinal disease in five and menorrhagia in one), and in two others folate deficiency coexisted. Biotin deficiency developed in three patients, manifested by dry eyes and angular cheilitis or hair loss. Vitamin A deficiency resulting in visual disturbance developed in one patient who was not receiving multivitamin supplements at that time. Serum levels of zinc, copper, selenium, manganese, vitamin A, and vitamin E were measured in 32 patients. No patient had normal levels of all six micronutrients. Nevertheless, there was no clinical evidence of toxicity or deficiency in any of these patients at the time assays were performed. In conclusion, abnormalities of micronutrient status are common in HPN patients, but serious sequelae appear to be unusual.