A retrospective archival study of 129 moderate to severe closed head-injury patients from a university-based rehabilitation hospital was conducted to investigate the effect of blood alcohol level (BAL) at time of trauma on the length of post-traumatic amnesia (PTA), length of hospitalization and cognitive status on clearing PTA. While no statistical significance was obtained for the effect of BAL on length of PTA, a mean difference of 15–4 days between‘no alcohol’and‘intoxicated’patient groups was observed. A low, but significant correlation,r =0–249,p<0.05, indicated that as blood alcohol level increased, time to rehabilitation admission increased. The sex of the patient had a significant effect on length of PTA, BAL and time of recovery variableF(6,81) = 2.468,p<0.05. Females experienced longer length of PTA, but had lower BALs than males. Measures of cognitive status on clearing PTA did not show a statistically significant effect of BAL. Results are discussed in terms of mediating variables in the relationship between BAL and the length of acute hospitalization, prolonged PTA in patients with a positive BAL, and potential physiological bases for the interaction among sex, BAL and PTA duration.