Background: Localized fibrous mesotheliomas are rare intrathoracic tumors arising from the pleural tissue. They are mostly benign tumors, with dimensions ranging from a small nodule to a large intrathoracic tumor. Case: This paper describes the presence of giant localized fibrous mesothelioma filling the lower left pleural cavity, which developed over a 20-year period. Surgical resection of the tumor showed a large, localized fibrous mesothelioma 14 cm in diameter. Conclusions: The clinical manifestations of localized fibrous mesotheliomas are very variable. Small tumors may be asymptotic, while large tumors may cause respiratory, cardiac or metabolic symptoms. Complete surgical resection is the preferred treatment and is usually curative. Careful follow-up is indicated because recurrence may occur, even many years after the initial operation.