Additional fractures occur in association with proximal radius fractures, but the extent of these secondary injuries has not been systematically assessed. To ascertain the frequency and nature of additional fractures associated with proximal radius injuries in a large pediatric cohort. Radiographs meeting search criteria for proximal radius fracture during a 5-year period were reviewed. Fracture characteristics and the coexistence of additional elbow fractures were recorded and analyzed. The retrospective review was compared with initial interpretation and a blinded review by two pediatric musculoskeletal radiologists. Four hundred ninety-four proximal radius fractures were included. The radial neck was the most common fracture site (89%). Neck fractures occurred in younger patients (mean: 7.3 years) than head fractures (mean: 13.3 years) (P<0.001). Additional elbow fractures occurred in 39%, most commonly at the olecranon (22%). Additional fractures occurred in younger patients (mean: 7.2 years) than isolated proximal radius fractures (mean: 8.5 years) (P<0.001). Elbow joint effusion and complete or displaced radius fractures were each associated with additional elbow fractures (P<0.001). When compared with initial interpretation, 25% of additional fractures were not identified on initial radiographs, of which 44% were occult retrospectively. Fracture identification demonstrated excellent inter-reader reliability (interclass correlation coefficient [ICC]: 0.88, 0.94), but joint effusion interobserver agreement was only fair (ICC: 0.52, 0.41). Proximal radius fractures in children often occur in association with other elbow fractures, most commonly involving the olecranon. Enhanced awareness of these fracture patterns, especially in the setting of joint effusion or complete and displaced radius fractures, may improve detection to guide appropriate management.