Primary lymphoma of bone is an unusual extranodal presentation of pediatric non-Hodgkin's lymphoma (NHL). Treatment with radiotherapy alone has resulted in a disease-free survival rate of approximately 50% in most adult series. Between January 1973 and April 1985, 11 children with biopsy-proven NHL of bone were seen and treated at our institutions. The minimal clinical staging included chest and bone radiographs, a radionuclide bone scan, complete blood cell counts and serum chemistries, and a bone marrow aspirate and biopsy. The age range was 9 to 17 years with a median age of 14 years. Histology included diffuse lymphoblastic lymphoma in four patients and diffuse histiocytic lymphoma in seven. Each patient was treated with the Adriamycin/prednisone/Oncovin (APO) protocol and ten patients received concomitant radiation to the whole bone when possible and a boost to the primary lesion(s). The median tumor dose was 5,000 rad (range, 3,600 to 5,600). The median follow-up was 8 years. There have been no relapses, but two patients have developed second bone tumors 5 and 7 1/2 years after beginning therapy. Each second tumor arose directly in the radiation field. The overall 8-year actuarial survival is 83%. We conclude that APO and local radiation results in excellent overall survival for children with primary NHL of bone. The occurrence of two second bone tumors, however, raises questions regarding dose and/or the role of radiation for this disease.