OBJECTIVE: Nocturnal enuresis is defined as involuntary emptying of the bladder in the absence of an organic cause in a child aged 5 years or older. Primary nocturnal enuresis (PNE) is the term used if the child has never been dry. Of several factors implicated in the etiology of PNE, genetic factors appear to be the strongest. In about 75% of affected children, there is a strong family history. The purpose of this study was to examine the genetic basis of nocturnal enuresis among children in the United Arab Emirates (UAE). METHODS: Chromosomes 12 and 13 were genotyped in all family members of 10 affected children in four large families. Linkage to earlier reported microsatellite markers on these two chromosomes was examined. RESULTS: In the four families examined, we did not find evidence for linkage to the two loci reported previously. CONCLUSIONS: Among UAE children examined, no linkage was found between PNE and the loci reported previously on chromosomes 12 and 13, indicating further genetic heterogeneity in PNE.