Objective To determine the prevalence of additional injuries or bleeding disorders in a large population of young infants evaluated for abuse because of apparently isolated bruising. Study design This was a prospectively planned secondary analysis of an observational study of children <10 years (120 months) of age evaluated for possible physical abuse by 20 US child abuse teams. This analysis included infants <6 months of age with apparently isolated bruising who underwent diagnostic testing for additional injuries or bleeding disorders. Results Among 2890 children, 33.9% (980/2890) were <6 months old, and 25.9% (254/980) of these had bruises identified. Within this group, 57.5% (146/254) had apparently isolated bruises at presentation. Skeletal surveys identified new injury in 23.3% (34/146), neuroimaging identified new injury in 27.4% (40/146), and abdominal injury was identified in 2.7% (4/146). Overall, 50% (73/146) had at least one additional serious injury. Although testing for bleeding disorders was performed in 70.5% (103/146), no bleeding disorders were identified. Ultimately, 50% (73/146) had a high perceived likelihood of abuse. Conclusions Infants younger than 6 months of age with bruising prompting subspecialty consultation for abuse have a high risk of additional serious injuries. Routine medical evaluation for young infants with bruises and concern for physical abuse should include physical examination, skeletal survey, neuroimaging, and abdominal injury screening.