Objectives: Micronutrient supplementation in critically ill adults remains controversial. In the pediatric setting, the impact of oxidative stress on the overall micronutrient status has been poorly explored, due to the limited number of studies and to confounding factors (i.e., malnutrition or extra losses). In order to better understand this phenomenon, we aim to describe micronutrient status, focusing on seven micronutrients, in well-nourished critically ill children presenting with severe oxidative stress. Design: Prospective, transversal, observational, single-center study. Setting: PICU, and anesthesiology department, Lyon, France. Patients: Three groups of patients were clinically defined: severe oxidative stress PICU group (at least two organ dysfunctions), moderate oxidative stress PICU group (single organ dysfunction), and healthy control group (prior to elective surgery); oxidative stress intensity was controlled by measuring plasma levels of glutathione peroxidase and glutathione. Children presenting any former condition leading to micronutrient deficiency were excluded (malnutrition, external losses). Interventions: Plasma levels of selenium, zinc, copper, vitamin A, vitamin E, vitamin C, and ?-carotene were measured in PICU oxidative stress conditions and compared with those of healthy children. Measurements and Main Results: Two hundred one patients were enrolled (51, 48, and 102 in severe, moderate, and healthy control groups, respectively). Median age was 7.1 years (interquartile range, 2.1-13.8 yr). There was a significant trend (p < 0.02) toward plasma level decrease of six micronutrients (selenium, zinc, copper, vitamin E, vitamin C, and ?-carotene) while oxidative stress intensity increased. Biological markers of oxidative stress (glutathione peroxidase and glutathione) were in accordance with the clinical definition of the three groups. Conclusions: A multiple micronutrient deficiency or redistribution occurs in critically ill children presenting with severe oxidative stress. These findings will help to better identify children who might benefit from micronutrient supplementation and to design adapted supplementation trials in this particular setting.