Enuresis is a disease of complex pathogenicity. Most monosymptomatic bedwetters have either normal bladder function and capacity and large urine production at night-time, or slightly increased micturition frequency during the day, normal circadian rhythm and small bladder capacity at night-time. In some studies, patients who failed to become dry when using alarm treatment had normal bladder function and capacity with large urine production at night. This same group of patients showed an excellent response to desmopressin treatment. Recent studies have also looked at the possible relationship of natriuresis or calciuria in monosymptomatic enuresis. The molecular genetic aspects of enuresis are attracting increased attention. Studies have substantiated the involvement of numerous loci on certain chromosomes; in excess of 10 chromosomes are thought to be involved. Rare enuresis subtypes include night-time natriuretics with or without polyuria, calciuria and airway obstruction-induced bedwetting. The role of bladder dysfunction in monosymptomatic bedwetting remains undetermined.