A case control study design was used to determine the risk factors for severe injuries associated with falls from playground equipment. Children presenting to the Hospital for Sick Children in Toronto because of falls from playground equipment (1995-1996) were identified through daily review of admissions and emergency department visits. Cases were defined as children with a severe injury (AIS > or = 2), whereas, controls were children with a minor injury (AIS < 2). Data on age, sex, socioeconomic status, prior experience on the equipment, previous playground injury, type of equipment, height of fall, undersurface, nature of injury, body part involved, and disposition were collected via telephone interview, field trip measurement, and mailed questionnaire. A total of 126 children were studied--67 cases and 59 controls. There were no differences between the two groups on age, sex, socioeconomic status, prior exposure to the equipment, or previous playground injury. Extremity fractures predominated in the case group, while, facial lacerations predominated in the control group. The median height of fall for cases was 199 cm, compared with 160 cm for controls (P = 0.021). Cases were also more likely to have fallen from a height of > 150 cm (73%), compared with controls (54%), P = 0.027. The majority of cases (82%) and controls (86%) fell onto an impact absorbing undersurface (P = 0.540). The median depth of impact absorbing undersurface, however, for both case and control injuries was 3 cm--well below the recommended safety standards. Height of fall was an important risk factor for severe injury associated with falls from playground equipment. Above 150 cm, the risk of severe injury was increased 2-fold.