Introduction: the prevalence of malnutrition in the pediatric hospital population ranges between 6 and 50 % in different countries. It is necessary to quantify the prevalence of risk or malnutrition at hospital admission in Colombia. Objective: to estimate the prevalence of intrahospital nutritional status using standardized reference standards and to perform the operational diagnostic by evaluating assessment of malnutrition of the STRONGkids tool in children hospitalized in a highly complex healthcare institution. Materials and methods: a descriptive cross-sectional study was carried out in which pediatric patients were selected consecutively for 5 weeks. The population would correspond to 300 patients. Results: the prevalence of some degree of hospital malnutrition was 3.5 % (95 % CI, 0.3-11) in children under 5 years of age and 3.8 % (95 % CI, 0.8-10.6) in older children. The STRONGkids tool, with a high risk classification, showed an average sensitivity of 81 % (95 % CI, 40 %-100 %), and average specificity of 97.9 % (95 % CI, 94.5 %-100 %) in the diagnosis of Malnutrition, according to the anthropometric criteria of Resolution 2465 of 2016 of the Ministry of Health. Conclusion: STRONGkids is a valid tool in the diagnosis of any type of hospital malnutrition in children.