CONCLUSION The main objective of this study was to analyze the incidence and risk factors for the occurrence of rare chromosomal anomalies and genetic disorders in children from 2005 to 2015 at the Department of Genetics and Metabolic Diseases, Department of Pediatrics, University Hospital Center Osijek. STUDY DESIGN We retrospectively analyzed medical records at the Department of Genetics and Metabolism, Department of Pediatrics, University Hospital Center Osijek. The methods in this study included a retrospective analysis of medical records and statistical data. PARTICIPANTS AND METHODS The study included patients who were treated at the Department of Genetics and Metabolism, Department of Pediatrics, University Hospital Center Osijek from 2005 to 2015. The inclusion criteria in the study are set and confirmed diagnosis of a rare chromosomal or genetic abnormality and children age of the respondents. RESULTS The study included 106 patients with confirmed diagnosis of a rare disease in children, of which there were 56 boys and 50 girls. The median age was 2 years. Most children had differences in phenotype, psychomotor development and IQ. Age of parents, qualifications and consanguinity are not proved to be risk factors for developing a disease. Most of the pregnant women had uneventful course of pregnancy and delivery schedule, which means that these data cannot indicate the presence or absence of rare diseases in child. OBJECTIVES The diagnosis of rare diseases is very important, but very difficult due to the extremely large number of these diseases and the lack of methods of diagnosis for less explored diseases. Furthermore, diagnosis is difficult due to lack of financial resources for acquiring technical support in confirming the diagnosis of those diseases for which there are diagnostic methods.