To evaluate the diagnostic yield of the procedure, mucosal-incision assisted biopsy (MIAB), for the histological diagnosis of gastric gastrointestinal stromal tumor (GIST), we performed a retrospective review of the 27 patients with suspected gastric GIST who underwent MIAB in our hospitals. Tissue samples obtained by MIAB were sufficient to make a histological diagnosis (diagnostic MIAB) in 23 out of the 27 patients, where the lesions had intraluminal growth patterns. Alternatively, the samples were insufficient (non-diagnosticMIAB) in remaining 4 patients, three of whom had gastric submucosal tumor with extraluminal growth patterns. Although endoscopic ultrasound and fine needle aspiration is the gold standard for obtaining tissue specimens for histological and cytological analysis of suspected gastric GISTs, MIAB can be used as an alternative method for obtaining biopsy specimens of lesions with an intraluminal growth pattern. To evaluate the diagnostic yield of the procedure, mucosal-incision assisted biopsy (MIAB), for the histological diagnosis of gastric gastrointestinal stromal tumor (GIST), we performed a retrospective review of the 27 patients with suspected gastric GIST who underwent MIAB in our hospitals Tissue samples obtained by MIAB were sufficient to make a histological diagnosis (diagnostic MIAB) in 23 out of the 27 patients, where the lesions had intraluminal growth patterns. Alternatively, the samples were insufficient (non-diagnostic MIAB) in remaining 4 patients, three of whom had gastric gastric mucosal tumor with extraluminal growth patterns. Although endoscopic ultrasound and fine needle aspiration is the gold standard for obtaining tissue specimens for histological and cytological analysis of suspected gastric GISTs, MIAB can be used as an alternative method for obtaining biopsy specimens of lesions with an intraluminal growth pattern.