Extensive studies of the epidemiology of nocturnal enuresis (NE) in Western countries indicate that the prevalence of this condition is relatively high (7-10% of children aged 7 years are enuretic). In the current study, questionnaires to assess the epidemiology of NE in Hong Kong were completed by 3521 school children, aged 4-12 years, the majority of whom (99.8%) were ethnic Chinese. Analysis of these questionnaires revealed a lower prevalence of monosymptomatic NE in this population of children (3.5%) compared with the results of studies conducted in Western countries. Furthermore, NE was found to be associated with arousal difficulties, nightmares, a positive family history of enuresis, poor school performance and poor relationships with classmates. A second study conducted to evaluate the response to desmopressin treatment of 25 children with severe monosymptomatic NE showed that 84% had a good response (> 50% reduction in the number of wet nights). Taken together, the results of these studies suggest that children with NE in Hong Kong may represent a more homogeneous population than in other countries, and that there is a strong genetic component in the aetiology of NE in this country. These children appear to be particularly responsive to treatment with desmopressin.