Attention deficit hyperactivity disorder (ADHD) is a common disorder of the school age population. ADHD has been shown to be familial, and genetic studies estimate its heritability at 80%-90%. The aim of the present study was to investigate the association between the genetic type and alleles for the HTR1A gene in Korean children with ADHD. The sample consisted of 142 ADHD children and 139 control children. We diagnosed ADHD according to the Diagnostic and Statistical Manual of Mental Disorders-4th edition. ADHD symptoms were evaluated with Conners' Parent Rating Scales and Dupaul Parent ADHD Rating Scales. Blood samples were taken from the 281 subjects, DNA was extracted from blood lymphocytes, and polymerase chain reaction was performed for HTR1A polymorphism. Alleles and genotype frequencies were compared using the chi-square test. We compared the allele and genotype frequencies of HTR1A gene polymorphism in the ADHD and control groups. This study showed that there was a significant correlation among the frequencies of the rs10042486 (OR=1.55, 95% CI=1.02-2.30, p=0.041), rs1423691(OR=1.55, 95% CI=1.02-2.30, p=0.041),and rs878567(OR=1.60, 95% CI=1.06-2.43, p=0.027) alleles of HTR1A, but the final conclusions are not definite. Follow-up studies with larger patient or pure subgroups are expected. These results suggested that HTR1A might be related to ADHD symptoms.