We report two cases, of 48- and 53-year-old women, with huge intrathoracic extrapulmonary tumors which originated from the diaphragm. In these cases the totally resected tumors were examined histologically and immunohistochemically, and based on these studies benign localized solitary fibrous tumors originating from the diaphragmatic pleura were diagnosed. We observed no recurrence in the long-term follow-up, which was necessary for these cases due to the tumors' unpredictable clinical behavior even when they were thought to be benign histologically. Because of the huge sizes of these tumors, originating from the diaphragmatic pleura with pedicles, and benign clinical outcome correlating with the histological examination, these cases are thought to be worthy of interest.