The aim of the study was to find an association between dopamine receptorD4 (DRD4) polymorphism and Attention Deficit Hyperactivity Disorder(ADHD) and to explore the possibility of autistic symptoms in ADHD andtheir relation to DRD4. It is a case-control study conducted on 37 ADHDand 32 control Egyptian children (ages 6-12). Cases were assessed by apsychiatric semi-structured interview, the Conners’ Parent Rating Scale, andthe Social Responsiveness Scale (SRS). PCR was done to detect thepolymorphism. A significant association was found between ADHD and the4R allele of DRD4; however, no association was found with the 7R allele. Inaddition, some environmental and associated factors were found to berelevant to ADHD. Autistic symptoms were found in ADHD children andthere was no relation detected between these symptoms and DRD4.