8 patients with plasmocytomas were treated with Endoxan and compared with 5 patients without any considerable treatment. Diagnosis, therapy and prognosis of plasmocytoma are discussed. Particularly mentioned are 3 patients with secondary tumours during cytostatic treatment, a plasmocytoma without paraprotein, a tumorous plasmocytoma with double paraproteinemia and a gammopathia with further development into a plasmocytoma 10 years later.