We performed a retrospective review of 34 humerus shaft fractures (HSFs) in children younger than 3 years to determine the frequency of child abuse in young children with this injury. Data were obtained from hospital records (including previous and subsequent emergency, clinic, and inpatient notes), radiographs, and county childprotective services. Cases were reviewed independently by four physicians and were classified as probable abuse, probable not abuse, and indeterminate. Only 18% were classified as probable abuse. The history and findings other than the fracture itself were critical in establishing cause. Neither age nor fracture pattern is pathognomonic of abuse, but suspicion should remain high. A detailed history, complete physical examination, and appropriate radiographic investigation are required in every case either to make the diagnosis of abuse or to avoid the trauma of a false accusation.