BACKGROUND:,The objective of the present study was to determine the prevalence pattern of Down Syndrome (DS) in children < 5 years of age in the State of Qatar. This is a retrospective descriptive study. The study was conducted in the Hamad General Hospital, Women's Hospital, and Rumailah Hospital (Hamad Medical Corporation). A total of 146 children were reported as having DS during the 6-year period from I January 2000 to December 31, 2005. METHODS: The diagnostic classification of definitive DS was made in accordance with criteria based on the International Classification of Disease 10th Revision (ICD-10). The data collected from the medical records included sociodemographic characteristics of the children, genetic and family history, pedigree analysis, and clinical genetic examination. RESULTS: A total of 146 children were diagnosed with DS during the last 6-year period and the prevalence rate is 19.5 per 10,000 live births. Of these, 40.4% were Qataris and 59.6% were non-Qataris. DS was slightly more common in boys (52.7%) than girls (47.3%). Infants < 1 year old had the high. est frequency of DS (40.4%), followed by children (1-2) years (26%). The most common abnormality was regular trisomy (98%). Also, one-half of the studied children had congenital heart problems (51.7%), There is a significant relationship between DS and maternal age as reported by other studies in other countries. CONCLUSION: The identification of specific types of chromosomal abnormalities in DS children is important as it enables clinicians to accurately counsel the parent regarding the recurrence risk and available options.