In anticipation of a consortium study of methotrexate (MTX) therapy provided to patients with primary central nervous system lymphoma (PCNSL) we have provided intravenous MTX without irradiation therapy to 31 nonimmunosuppressed individuals. Twenty (65%) achieved complete response and 11 (35%) partial response to therapy. For the 31 patients the median survival was 30.43 months with an actuarial median follow-up time of 30.69 months. The 2+ year survival was 63% for all patients and 90% for complete responders. Of 375 drug cycles, grade 3 leukopenia was identified in 3 cycles, mucositis in 6 cycles and delayed drug clearance in 47 cycles. Recurrences included brain (9/20) and/or spinal fluid (2/20). The median Karnofsky scale improved from 40 (10-80) prior to therapy to 90 after treatment. Eleven patients, in complete response for a median of 22+ months after diagnosis were evaluated using 4 instruments that assess Quality of Life Functional Assessment of Cancer Therapy - Brain (FACT-BR) modified, Symptom Questionnaire, Social Adjustment Scale-Self-Report and Problem Solving Inventory. Their psychosocial adjustment, well-being and stress coping abilities were comparable to the normative groups. Further there was no evidence of any MTX-induced, Magnetic Resonance Imaging (MRI)-detected encephalopathy in these individuals and there was preservation of clinical cognition and memory. We conclude that therapy with MTX, without radiation can be used in PCNSL patients without limitations of age or pretreatment Karnofsky scores. Further rates of response and median survival approach those of therapies using multiple drugs and radiation, but with a less likely risk of dementia.