A rare case of an initial presentation of a metastatic lesion on the gingiva, arising from malignant fibrous histiocytoma (MFH) of the lung is reported. The role of electron microscopy in the diagnosis of soft tissue sarcomas has been studied. The ultrastructural details of a MFH are described and illustrated. The patient died within 9 weeks of the initial presentation with a gingival mass as is normal in these cases. He developed metastatic disease of the liver, lymph nodes, and bone. The role of electron microscopy in the diagnosis of soft tissue sarcomas is discussed.