Background: Little research has been done on the nutritional behavior of children and adolescents with phenylketonuria (PKU) and this could contribute to clarifying the controversial question of whether this group of patients has a higher risk of obesity due to the special nutritional requirements. The aim of this study was to compare the nutritional status, food intake and quality of nutrition of underage patients with PKU during rehabilitation and at home with a metabolically healthy control group and to derive possible obesity risk factors from this. Methods: 15 patients with PKU (47% female, 12 +/- 2 years) were compared with 15 matched controls (47% female, 12 +/- 2 years). Anthropometry, body composition (BIA), food intake (3-day weighing protocol) and food quality were recorded using the Healthy Eating Index of the European Prospective Investigation into Cancer and Nutrition (HEI-EPIC). Results: Body weight, body mass index, waist circumference, lean mass, fat mass, and diet quality were not different between participants with PKU and their controls. During rehabilitation, the consumption of vegetables and fruit was too low in both groups, while the consumption of fat and sugar was too high. Only fat consumption tended to be higher in the PKU group than in the controls (PKU 3.7 vs. controls 2.9 portions/day, p=0.062). Summary: The nutritional status and quality of nutrition in young patients with PKU were comparable to age-matched, metabolically healthy controls and could be improved. Despite equivalent obesity risk factors, improving the nutritional quality of patients with PKU through professional nutritional advice seems to make sense for the prevention of obesity.