Child malnutrition has a significant effect on growth and development and it has various clinical consequences. Screening tests are used to detect an early malnutrition or the risk of the development of malnutrition and among the tests for children in Europe, the STRONGkids test has been the most successful. The study included two groups of children and adolescents aged between 1 and 19 years. In the first group, there were children hospitalized in the Clinic of Pediatrics of the University Medical Centre Ljubljana. In the second group, there were healthy children who came to the systematic medical examination in the health care center. The study included 234 healthy and 151 hospitalized children. The STRONGkids screening tool was used to determine children with risk of malnutrition. Then, we performed anthropometric measurements (body height, mass, body mass index, skinfold measurements, and the calculation of body fat percentage) with the same children and compared them with the standards for children with the same age and gender. Finally, we compared the number of children with malnutrition recognized by using anthropometric measurement with the number of children with an increased risk for malnutrition development according to the results of the STRONGkids screening tool. Among the group of healthy children we found a moderate risk of malnutrition at only 4.7 % of children. In the hospitalized group of children, the percentage of children with a high risk of malnutrition was 9.9 %. A moderate risk of malnutrition was 47.7 %. The percentage of malnourished children in the hospital group of children was 13.2 % according to the anthropometric measurements, and 17.5 % due to the skinfold measurement. In the healthy group of children, we recognized 0.4 % malnourished children due to the anthropometric measurements and 14.3 % due to the skinfold measurement. The STRONGkids test proved to be very sensitive, well specific and accurate, with a low positive and high negative predictive value. The STRONGkids test could be used as a screening tool for hospitalized and healthy children.