OBJECTIVE Benign external hydrocephalus (BEH) is an enlargement of the subarachnoid spaces (SASs) that can be seen in young children. It is controversial whether children with BEH are predisposed to developing subdural hemorrhage (SDH) with or without trauma. This issue is clinically relevant as a finding of unexplained SDH raises concerns about child abuse and often prompts child protection and law enforcement investigations. METHODS This retrospective study included children (1-24 months of age) who underwent head CT scanning after an accidental fall of less than 6 feet. Head CT scans were reviewed, cranial findings were documented, and the SAS was measured and qualitatively evaluated. Enlarged SAS was defined as an extraaxial space (EAS) greater than 4 mm on CT scans. Clinical measurements of head circumference (HC) were noted, and the head circumference percentile was calculated. The relationship between enlarged SAS and HC percentile, and enlarged SAS and intracranial hemorrhage (ICH), were investigated using bivariate analysis. RESULTS Of the 110 children included in this sample, 23 had EASs greater than 4 mm. The mean patient age was 6.8 months (median 6.0 months). Thirty-four patients (30.9%) had ICHs, including subarachnoid/subpial (6.2%), subdural (6.2%), epidural (5.0%), and unspecified extraaxial hemorrhage (16.5%). Enlarged SAS was positively associated with subarachnoid/subpial hemorrhage; there was no association between enlarged SASs and either SDH or epidural hemorrhage. A larger SAS was positively associated with larger HC percentile; however, HC percentile was not independently associated with ICH. CONCLUSIONS Enlarged SAS was not associated with SDH, but was associated with other ICHs. The authors' findings do not support the theory that BEH predisposes children to SDH with minor accidental trauma.