Functional urinary incontinence in children may be caused by disturbances of the filling phase, the voiding phase or a combination of both. Detrusor overactivity may cause frequency and urgency, with or without urge incontinence. Girls present with symptoms of detrusor overactivity more often than boys, but sometimes other symptoms, e.g. urinary tract infections or constipation, prevail. Frequent contractions of the detrusor may cause the pelvic floor muscles to become overactive, resulting in staccato or fractionated voiding. When incontinence is the result of a voiding disorder the term 'dysfunctional voiding' is used. Bladder function in these children may be normal, but instability may be present. In children with a 'lazy' bladder, voiding occurs with no detrusor contractions, and postvoid residual volumes and overflow incontinence are the main characteristics. Diagnosis is based on the medical and voiding history, a physical examination, bladder diaries and uroflowmetry. The upper urinary tract should be evaluated in children with recurrent infections and dysfunctional voiding (reflux). Uroflowmetry can be combined with pelvic floor electromyography to detect overactivity of the pelvic floor muscles. Urodynamic studies are usually reserved for patients with dysfunctional voiding and those not responding to anticholinergic drugs. Treatment is usually a combination of 'standard therapy', behavioural therapy, bladder training, physiotherapy and medical treatment. The role of alpha-blockers needs to be evaluated further. Also, neuromodulation may have a place in treatment but the exact indications need to be defined. Clean intermittent self-catheterization is sometimes necessary in children with a lazy bladder and large residual volumes who do not respond to a more conservative approach. Future research needs to be directed towards improving understanding of the pathophysiology, epidemiology, classification and treatment modalities of functional incontinence in children.