Short stature has been reported in congenital ichthyoses (CI) but little data exist on patients' nutritional status.To describe the nutritional status at the first evaluation of children and young adults with CI.Prospective observational study of patients assessed at a multidisciplinary clinic. Clinical variables and ichthyosis severity were collected. Anthropometric assessment was made measuring weight and height and nutritional status was classified based on the WHO definitions for malnutrition. Analytical assessment included markers of nutritional status, fat soluble vitamins and micronutrients.We included 50 patients with a median age of 5 years (IQR 1.6-10.3). Undernutrition was found in 32% of patients and 75% of the undernourished children presented growth impairment. Younger children and those with severe ichthyoses were the most affected. Micronutrient deficiencies were found in 60% of patients. Deficiencies of selenium (34%), iron (28%), vitamin D (22%) and zinc (4%) were the most frequent findings.Our small sample includes a heterogeneous group of ichthyoses.Children with CI appear to be at risk of undernutrition especially at younger ages. Nutritional deficiencies are common and should be monitored. Growth failure in children with ichthyosis could be caused by undernutrition and aggravated by nutritional deficiencies.