The purpose of this study is to report the results of megavoltage irradiation in 23 previously unreported cases of extramedullary plasmacytoma of the head and neck. It has been found that 3500 cGy (rad) in three weeks provides good local control of disease with minimal morbidity and a significant proportion do not go on to multiple myeloma. Prognostic factors of significance with respect to subsequent development of multiple myeloma include site and presence or absence of bone destruction. The presence or absence of an M protein peak appears to be of no significance.