Background: Several studies have confirmed that endothelin and endorphin are involved in the occurrence of cerebral vasospasm. However, the correlation of these factors to acute cerebral infarction-related risk factors needs to be confirmed. Objective: To detect endothelin-1 (ET-1) and beta-endorphin (β -EP) levels in plasma of patients with acute cerebral infarction, and to analyze the correlations of these factors to smoking, alcohol abuse, hypertension, diabetes mellitus, diseased region, diseased degree, gender, and other factors related to acute cerebral infarction. Design: A case-control observation. Setting: First Department of Neurology, Guangdong Hospital of Traditional Chinese Medicine; Department of Neurology, Second Affiliated Hospital of Sun Yat-sen University. Participants: Sixty-nine inpatients with acute cerebral infarction were admitted to the Department of Neurology, Second Affiliated Hospital of Sun Yat-sen University (March 2003-January 2004) and First Department of Neurology, Guangdong Hospital of Traditional Chinese Medicine (March - July 2004) and recruited for this study. All 69 inpatients corresponded to the diagnosis criteria of acute cerebral infarction, formulated in the National Working Conference of Cerebrovascular Disease in 1998, and were confirmed as acute cerebral infarction by CT/MRI. The patient group consisted of 35 males [(64±12) years old] and 34 females[ (67 ± 13) years old]. Among them, 9 patients were smokers, 7 were alcohol users, 48 had a history of hypertension, and 16 had a history of diabetes mellitus. CT/MRI examinations revealed that 35 patients presented with left focus sites, 11 with right ones and 23 with bilateral ones. Following attack, 24 patients had Barthel Index Scale grading < 40 points, 21 patients 40-60 points, and 24 patients > 60 points. An additional 59 healthy individuals, who received health examinations simultaneously, were included as controls. Among the control subjects, there were 37 males [(62±10) years old] and 22 females [(65±11) years old]. Among them, 7 patients were smokers, and 6 were alcohol users. All controls had no history of stroke, hypertension, or diabetes mellitus. Informed consents of laboratory measurements were obtained from all subjects, and this study was approved by the Hospital Ethics Committee, Methods: 1 Following admission, all subjects were scored by Barthel Index Scale (BIS) and Hamilton Depression Scale. Meanwhile, hypertension, diabetes mellitus, gender, smoking, drinking, and other conditions were recorded. CT/MRI examination was conducted to identify the focus site. 2 On the 2nd day after admission, ET-1 and β -EP plasma levels were measured with an automatic ET-1 and β -EP analysis kit. Main outcome measures: ET-1 and, β -EP plasma levels and their correlation to acute cerebral infarction-related factors. Results: Sixty-nine patients with acute cerebral infarction, and an additional 59 healthy individuals participated in the final analysis. 1 ET-1 [(63.80±27.65) ng/L vs. (46.50±9.36) ng/L, P < 0.05] and β -EP [(94.18±33.94) mg/L vs. (51.87±23.43) mg/L, P < 0.05] levels of the patient group were obviously higher than respective values of the control group. 2 The ET-1 and β -EP levels of patients with cerebral infarction did not correlate to hypertension, diabetes mellitus, BIS, depression, cerebral infarct focus, disease course, gender, smoking or drinking (P > 0.05). Conclusion: The ET-1 and β -EP levels of patients with acute cerebral infarction increased, but they were not obviously associated with disease course, blood pressure, blood glucose, BIS, or other common cerebral infarction-related factors.