To study polymorphisms of dopamine D4 receptor (DRD4) in children with primary nocturnal enuresis (PNE) and explore the relationship between DRD4 gene polymorphisms and PNE.Genomic DNA was isolated from leukocytes in 86 unrelated children with PNE and in 100 healthy unrelated children (controls). Polymorphisms of DRD4-1240L/S, -616C/G and -521C/T were genotyped by allele-specific primer PCR.There were significant differences in allele frequencies (x2=8.13, P<0.05) and genotypes frequencies (x2=6.23, P<0.05) of DRD4-616C/G between PNE patients and healthy controls. The frequency of haplotype LCT consisting of 3 function polymorphic sites DRD4-1240L/S, -616C/G and -521C/T in PNE patients was statistically higher than that in healthy controls (x2=5.88, P<0.05).The change of C to G of DRD4-616 may affect the induction and transcription of DRD4 gene. The haplotype LCT consisting of 3 function polymorphic sites DRD4-1240L/S, -616C/G and -521C/T may synergistically inhibit the transcription activity of DRD4 gene. This might lead to a reduction of DRD4 protein expression and cause nocturnal enuresis.