Solitary plasmacytomas are rare tumours. We report our experience from 25 solitary osseous and 18 solitary extramedullary plasmacytomas. 41 patients were given high voltage radiotherapy, usually 40 Gy in 20 fractions. Two patients with extramedullary plasmacytoma developed generalized disease, while ten patients with osseous plasmacytoma developed myelomatosis. Extramedullary plasmacytomas are usually cured by adequate local treatment, while in solitary osseous plasmacytomas the prognosis is more dubious.