Aim: The main aim of this work is to examine the presence and genetic forms of persons with Down syndrome, cytogenetically proven in the Laboratory of Human Genetics in Children's Clinical Hospital, in Clinical Hospital Centre in Split for a ten-year period, i.e. for the period from year 2009 to 2018. Methods: We have retrospectively examined the cytogenetic test results of children diagnosed with Down syndrome who are born in maternity wards of the following counties: Split-Dalmatia County, Zadar County, Šibenik-Knin County and Dubrovnik-Neretva County. The diagnoses have been made based on postnatal diagnosis by classical cytogenetic analysis, from peripheral blood samples in the Laboratory of Human Genetics. The data have been processed with regard to gender and genetic form. Results: In the ten-year period from 2009 to 2018, 169 of Down syndrome patients have been cytogenetically proven. Out of that number, 77 were female (45, 56%) and 92 were male (54, 44%). The greatest number of examinees was in 2013 (25), while the smallest number was in 2010, 2011 and 2018 (13). From the total number of 82 713 children born in the four counties previously mentioned, 169 of them are cytogenetically diagnosed with Down syndrome which makes its incidence 0, 20%. The most common genetic form is trisomy 21, all together 165 of them (97, 6%). Mosaicism and translocation as two other types of Down syndrome hold equal shares. Each of them occurs in two cases (1, 2%). Conclusions: Based on the above mentioned results we can conclude that our data correspond to the data about general population from bibliography, hence the hypothesis of this research is accepted.