According to randomization, the patients are allocated to either EUS-FNA by 22G needle or KHB consisting of forceps biopsy through mucosal incision by a needle knife, both with subsequent histological/cytological and immunohistochemical evaluation of the specimen. The success of tissue diagnostics was evaluated as well as the possibility to determine the mitotic activity in case of GIST. In case of failure of the initial method, the other method was performed (cross-over design). Patients are hospitalized and kept under observation during 24 hours after the biopsy.