BACKGROUND: Predicting the outcome of stroke during the acute phase is difficult. Accurate methods for predicting outcomes could assist clinicians and families to make correct decisions in resource-poor environments. OBJECTIVE: To determine thyroid hormone levels in patients with ischemic or hemorrhagic stroke at the early stage, and to investigate its correlation with stroke prognosis. DESIGN, TIME AND SETTING: A comparative, observational study was performed at the Department of Emergency, Tertiary-care University Affiliated Hospital from January 2004 to January 2006.PARTICIPANTS: A total of 113 patients presenting to the Emergency Department within 3 hours of stroke symptom onset were approached for enrollment in the study. The patients were diagnosed by computer tomography examination, and comprised 87 ischemic stroke and 26 hemorrhagic stroke patients. METHODS: Following a thorough history and examination by emergency physicians, venous blood samples were collected from each patient. Thyroid-stimulating hormone (TSH), free triiodothyronine (free T3), and free thyroxine (free T4) levels were measured using a chemiluminescence method. The nerve function of patients was evaluated with Glasgow Coma Scale (GCS) score, and the patients were accordingly assigned to two subgroups-mild stroke (GCS≥9) and severe stroke (GCS≤8). MAIN OUTCOME MEASURES: Blood levels of TSH, free T3 and free T4;mortality at 7 days. RESULTS: Mean TSH values in hemorrhagic stroke patients with GCS≤8 were significantly greater than those in ischemic stroke patients with GCS≤8 and GCS≥9 (P＜0.05). Compared with patients who survived, the highest TSH levels were detected in patients that had died within 7 days. Correlation analysis results revealed a significant negative relationship between GCS values and TSH levels in patients with hemorrhagic stroke (r=-0.552, P＜0.01), and no correlation was determined between GCS values and TSH levels in patients with ischemic stroke (r=0.239, P＞0.05). CONCLUSION: In patients with hemorrhagic stroke, high TSH levels were observed within the first 3 hours of stroke onset, which could be considered an indicator of poor prognosis.