Violence between siblings is prevalent, can have long-lasting negative effects, and yet it is often dismissed as normal. This study explores sibling violence (SV) documented in medical records of children hospitalized in a psychiatric hospital. Retrospective chart review was conducted of all medical records of children ages 5 years to 12 years, living with a sibling in the home, admitted during the 2007 calendar year to a northwestern psychiatric hospital that serves a five state area (N = 135). Using a data collection tool, quantitative and qualitative data were extracted from the charts, and descriptive statistical analysis was used to identify patterns and trends. The records showed that 103 (76%) of the 135 patients perpetrated SV and 30 (22%) were victims of SV. Many of the patients perpetrating SV were also violent toward themselves and toward peers, mothers, and teachers. The majority of patients did not have a psychiatric diagnosis that included violent behavior as a criterion and most of the patients had one or more past adverse experiences. Findings suggest that children hospitalized with psychiatric problems should be screened for SV perpetration and victimization, that health care staff and parents should be educated about SV, and that further research is needed to better understand what constitutes SV, the context within which it occurs, and effects of non-protection by parents.