Susceptibility weighted imaging (SWI) is a newly developed magnetic resonance (MR) protocol. Recent studies have found that SWI may be useful in the field of cerebrovascular diseases, especially for detecting the presence of prominent veins, microbleeds and the susceptibility vessel sign (SVS). Some authors have even suggested that SWI can be used to predict outcome. We conducted a prospective study of patients hospitalized with middle cerebral artery territory infarction receiving MRI within 2 days of stroke onset. The presence of prominent veins, microbleeds and SVS in SWI was analyzed along with hospital characteristics of the patients. A total of 44 patients were enrolled. Among the 44 patients, 15 (34.1%) patients showed prominent veins, 19 (43.2%) showed SVS, and 14 (31.8%) showed microbleeds. The presence of SVS and prominent veins was not associated with prognosis. Though not statistically significant (p = 0.06), patients with SVS were more likely to develop later brain edema. SVS was significantly associated with arterial occlusion (p = 0.008) based on the MR angiogram, and microbleeds were significantly associated with later hemorrhagic transformation (p = 0.018). In our study, SWI could not be used to predict outcome as previously suggested. However, the presence of microbleeds may predict further hemorrhagic transformation, and the presence of SVS could be used to detect intra-arterial thrombus. Patients with SVS were also more likely to develop later brain edema. Including SWI in routine MR protocols for major acute ischemic stroke would be worthwhile.