OBJECTIVE: To study the phenomenology, clinical correlates, and response to treatment of delirium in critically ill children in the pediatric intensive care unit (PICU). DESIGN, SETTING AND PATIENTS: Descriptive study of a cohort of child psychiatric consultations from a tertiary PICU between January 2002 and December 2005. Demographic data, clinical presentation, and response to treatment of children subsequently diagnosed with delirium were analyzed. RESULTS: Out of 877 admissions (age distribution 0-18 years) arose 61 requests for psychiatric assessment. Of the 61 children, 40 (15 girls and 25 boys) were diagnosed with delirium (cumulative incidence 5%; mean age 7.6 years). Age-specific incidence rates varied from 3% (0-3 years) to 19% (16-18 years). In addition to the classical hypoactive and hyperactive presentations, a third presentation was apparent, characterized mainly by anxiety, with a higher prevalence in boys. All but 2 of the 40 children received antipsychotic medication: 27 (68%) haloperidol, 10 (25%) risperidone, and 1 both in succession. Two children treated with haloperidol experienced an acute torticollis as side effect. All children made a complete recovery from the delirium; five, however, died of their underlying disease. CONCLUSION: The rate of delirium in critically ill children on a PICU is not negligible, yet prospective studies of the phenomenology, risk factors and treatment of childhood delirium are very rare. Once pediatric delirium has been recognized, it generally responds well to treatment.