Bedwetting (nocturnal enuresis) is common. It occurs in up to 20% of 5 year olds and 10% of 10 year olds, with a spontaneous remission rate of 14% per year. Weekly daytime wetting occurs in 5% of children, most of whom (80%) also wet the bed. Bedwetting can have a considerable impact on children and families, affecting a child's self-esteem and interpersonal relationships, and his or her performance at school. Primary nocturnal enuresis (never consistently dry at night) should be distinguished from secondary nocturnal enuresis (previously dry for at least 6 months). Important risk factors for primary nocturnal enuresis include family history, nocturnal polyuria, impaired sleep arousal and bladder dysfunction. Secondary nocturnal enuresis is more likely to be caused by factors such as urinary tract infections, diabetes mellitus and emotional stress. The treatment for monosymptomatic nocturnal enuresis (bedwetting with no daytime symptoms) is an alarm device, with desmopressin as second-line therapy. Treatment for non-monosymptomatic nocturnal enuresis (bedwetting with daytime symptoms--urgency and frequency, with or without incontinence) should initially focus on the daytime symptoms.Bedwetting without daytime symptoms, the most common toileting problem, can be effectively treated with an alarm device.