BACKGROUND: Global aphasia without hemiparesis (GAWH) is a rare stroke syndrome, which typically occurs after large perisylvian lesions involving both the Broca's and Wernicke's areas. This study localized the lesions and examined the pathogenic mechanism in Korean patients with GAWH. METHODS: Twelve patients were diagnosed with aphasia using the Western Aphasia Battery. To identify decreased perfusion, which might be functionally relevant to aphasia but not detected by diffusion weighted imaging (DWI), single photon emission tomography (SPECT) was performed in six patients. To uncover the possible pathogenic mechanisms of ischemic stroke, vascular and cardiologic work-ups were performed in all of the patients. RESULTS: The lesions seen on DWI varied, and included: both inferior frontal and superior temporal (four), isolated inferior frontal (four), superior temporal (one), subcortical (two), and even parieto-occipital (one) lesions. Brain SPECT did not reveal any extensive lesions of the peri-sylvian area outside the DWI lesion in any of the patients, except in one patient with subcortical lesions. CONCLUSIONS: Our results indicate that a single lesion of the left inferior frontal area, or a superior temporal lesion in different locations may produce GAWH, and the lesion profile and stroke mechanism in GAWH are heterogeneous, suggesting that lesions to an area of complex functional anatomy result in aphasia.