We evaluated the characteristics of children for whom critical incidents (CIs) were reported by performing prospective collection of patient data and retrospective review of reported CIs in a multidisciplinary neonatal-paediatric intensive care unit of a tertiary care university children's hospital. A period of 1 year was analysed (January to December 2007; 1,251 admissions). CIs comprised adverse events (actual patient injury), as well as near-misses. The report form of critical incidents was web-based and reporting was voluntary, anonymous and non-punitive. The severity of all CIs was divided into minor, moderate and major. Patients with and without CIs were compared regarding the following characteristics: Paediatric Index of Mortality (PIM2), duration of mechanical ventilation, length of stay in the intensive care, admission mode (surgery, cardiopulmonary bypass, cardiac/non-cardiac unit), age and sex. There were 360 CI reports (83 per 1,000 patient days; 13% major, 26% moderate, 61% minor severity). Of these, 310 CIs could be assigned to 198 specific patients. In the univariate analysis, patient-related risk factors for CIs were higher PIM2 score (p < 0.0001), increased length of stay (p < 0.0001), mechanical ventilation (p < 0.0001), increased ventilator days (p < 0.0001), male gender (p = 0.022) and young age (p < 0.0001). Using a logistic regression model, mechanical ventilation (p < 0.0001), male gender (p = 0.034) and length of stay (p < 0.0001) continued to be associated with the occurrence of CIs. Conclusion CIs often occur in paediatric intensive care. Among the patient-related factors, male gender, mechanical ventilation, and length of stay are independently associated with CIs. Already known at admission to intensive care are male gender and, usually, requirement for mechanical ventilation. Improved knowledge of the risk factors for CIs could help to minimize their frequency and thus improve quality of care.