The specific etiology of supracondylar humerus fractures in children is not well known. All supracondylar humerus fractures treated at Children's Hospital and Health Center, San Diego (CHSD) over an 8-year period (n = 391) were reviewed to determine specific information about the manner in which the injury occurred. Girls tended to sustain these fractures more often, and the nondominant arm was more often injured. Falls from a height accounted for 70% of the fractures. Children < or = 3 years old tended to fall off of household objects (beds, couches, other objects 3-6 feet high), and children 4 years and older tended to fall from playground equipment such as monkey bars, slides, and swings. Safety precautions should be implemented in homes of young children and at playgrounds to avoid these fractures.