OBJECTIVE: To investigate whether ischemic stroke severity differed among women who were receiving hormone replacement therapy (HRT) as compared with those who were not receiving these drugs. BACKGROUND: Estrogen has a neuroprotective effect in animal models of ischemic stroke, but data reflecting the impact of HRT on ischemic stroke severity in humans are lacking. METHODS: All women receiving HRT at the time of admission for acute ischemic stroke to an academic medical center over 3 years were identified by medical record review (n = 58). HRT users were matched with 116 HRT nonusers by age and number of stroke risk factors. Stroke severity was assessed retrospectively with the Canadian Neurological SCALE: Data were analyzed with nonparametric univariate tests (Spearman rank and chi(2) tests) and linear regression modeling using nonparametric matched-pair analysis. RESULTS: History of congestive heart failure or coronary artery disease (p = 0.01), atrial fibrillation (p = 0.02), and African American race (p = 0.04), were significantly associated with greater stroke severity in the univariate analysis. There was a nonsignificant trend toward lesser stroke severity in HRT users (median Canadian Neurological Scale score, 10, vs 9.5 in non-HRT users, p = 0.08). Multivariate analysis showed no independent effect of HRT use on stroke severity (F = 1.24, p = 0.17). CONCLUSIONS: There was no significant effect of HRT status on stroke severity. Because this was a retrospective analysis, prospective studies are also needed to further elucidate any potential neuroprotective effect of hormone replacement.