Malignant fibrous histiocytoma is the most common soft tissue sarcoma of late adult life, but it is rare in the pleura. We recently experienced a case of cytology of malignant fibrous histiocytoma in plural fluid. The smear revealed histiocytic malignant cells, spindle malignant cells and inflammatory cells. The histiocytic cells showed abundant, pale cytoplasm and ovoid, irregular eccentrically-placed nuclei. The spindle cells showed elongated nuclei. Intercellular collagen was also present.