Background/aims: The aim of this study was to evaluate the nutritional status of children at the moment of their hospitalization and to investigate whether there is a relation between the diagnosis and nutritional status. Methods: Patients hospitalized in the Children's Clinic of Cerrahpasa Medical Faculty (excluding emergency, newborn intensive care and newborn special care units) between December 2003 and August 2004 were included in the study. All patients' height, weight, weight for height head circumference, arm circumference, triceps skin-fold thickness, and Z results of the height and weight were measured and, in accordance with the anthropometric measurements at the moment of hospitalization, each patient's nutritional status was evaluated. The average of the values was compared to diagnosis. Results: 223 (42.2%) of a total of 528 patients were female. Patients' ages varied from one month to 23 years (5.8±5.3). The evaluated average height and weight Z scores of the patients were -0.6±1.9 and -0.7±1.5. Evaluation of height for age showed that in 27% of cases there was chronic malnutrition. Evaluation of weight for age and weight for height showed that in 52.4% and 40.9% of the cases, respectively, there was acute malnutrition. In 45.7% of the cases the body mass index was below -2 standard deviations. The evaluation of patients' diagnoses revealed 83 cases (15.7%) diagnosed as acute or chronic respiratory system disease. Malnutrition was most common among patients suffering from diseases from the following groups: chronic kidney insufficiency, genetic diseases, immune insufficiency and cystic fibrosis. Conclusion: Malnutrition among hospitalized children and especially those with chronic diseases is worth attention. Evaluation of the nutritional status and nutritional support are elements of the diagnostic and treatment process. In particular, closer observation and nutritional support are required in the cases of patients diagnosed with chronic kidney insufficiency, immune insufficiency, neurological diseases, and cystic fibrosis.