Alcohol withdrawal syndrome (AWS) manifests after alcohol-dependent individuals suddenly cease alcohol consumption. Clinical Institute Withdrawal Assessment-Alcohol, revised (CIWA-Ar) is a widely used tool to assess and guide treatment of AWS. CIWA-Ar was developed in voluntarily detoxification centers, and the reliability and validity of CIWA-Ar have been minimally evaluated in hospitalized patients. We performed a retrospective chart review of 479 cases of screening and treatment of AWS using CIWA-Ar, of which 118 were admitted to a trauma/orthopedic (T/O) service and 361 to an internal medicine (IM) service. Exploratory factor analyses with varimax rotation were applied for each population, and reliability testing was performed on the determined subscales. Exploratory factor analyses yielded 2 unique structures, each explaining 56% of the variance of CIWA-Ar. The IM group had a 3-factor structure with the Physical Disturbances (23%), Anxiety (19%), and Confusion (14%) subscales. The T/O group had a 2-factor structure with the Neurological Disturbances (36%) and Physical Disturbances (20%) subscales. Overall, Cronbach's alphas were acceptable (0.74 and 0.82 for IM and T/O, respectively); however, Cronbach's alphas for the IM subscales were 0.66 and 0.69 for physical disturbances and anxiety, respectively. Cronbach's alpha for the Confusion subscale was not calculated because only 1 scale item loaded. The subscales of the T/O factor structure yielded Cronbach's alphas of 0.81 for neurological disturbances and 0.62 for physical disturbances. Our analyses did not support the reliability or validity of CIWA-Ar in acutely ill or injured patients, warranting further investigation and tool development for AWS management in the hospital setting.