BACKGROUND Somatic development and respiratory function are the most important prognostic factors for the course of the disease and the expected lifespan of patients suffering from cystic fibrosis (cF). Aim of the study was to evaluate nutritional status and pulmonary function in children and adolescents suffering from cystic fibrosis. Pulmonary function was evaluated in relation to several factors connected to the course of the disease. METHODS Anthropometric and spirometric data were extracted from the medical histories of 89 children diagnosed and treated at the institute of Mother and child in Warsaw. Molecular DnA was analyzed in all the patients in order to determine the type of CFTR gene mutation. Anthropometric parameters were expressed in terms of standard deviations away from age-specific and sex-specific reference for the population of Warsaw. RESULTS the studied children were significantly shorter than healthy children. Ten of the children (11.2%) had severe growth disturbances. nutritional status was also adversely affected. Almost 50% of the children were mal-nourished. the children suffered from a deficit in muscularity and adiposity. The percent of predicted FeV1 was highest in those children who were well-nourished, and lowest in the severely malnourished patients. the effect of the nutritional status on pulmonary function was observed. CONCLUSIONS chronic infection by P. aeruginosa had a marked adverse effect on pulmonary function.