About 1% of healthy children over the age of 5 years have troublesome daytime wetting. Two-thirds of those who wet by day are reliably dry at night. The problem is more common in girls and is usually the result of urge incontinence. Although the wetting may be exacerbated by giggling and/or stress, pure giggle micturition and isolated stress incontinence are both rare. There is a strong association with bacteriuria (50% prevalence) in girls who wet by day. A potentially important relationship exists between day wetting, infection, reflux and upper tract damage, which is expressed in an extreme form in the syndromes of incoordinated voiding and progressive renal damage. Most children who wet by day have unstable bladders. Many of them adopt characteristic "holding" postures. There is an increased incidence of emotional disorder compared with children who merely wet the bed. Between 10% and 15% of children who wet by day become dry during the next 12 months. The acquisition of dryness is accelerated by eradication of bacteriuria and a sympathetic and energetic management regime, which should place responsibility on the child and result in the child voiding more frequently and completely. Reminder alarms and other behaviour therapies have proved effective. There is no satisfactory evidence for the efficacy of drugs. More complex behavioural training regimes including biofeedback are valuable for severe cases.