We have reported 14 primary non-Hodgkin's lymphomas of the brain seen in Calgary and Edmonton, Alberta, between 1975 and 1983. Eleven patients had histiocytic lymphoma while the remaining 3 were lymphocytic. The clinical presentations were extremely variable, with increased intracranial pressure (60%) and focal neurological deficits (60%) being most common. The most frequent appearance on computed tomographic scan was a hyperdense lesion of the cerebrum (44%); four cases had multifocal lesions. All patients had subtotal resection of the tumor. Two patients had surgery only and their mean survival was 3.5 months. Ten patients received whole brain irradiation, with 2 patients receiving a boost to the primary tumor site as well. The mean survival was 24.7 months. Two patients received chemotherapy in addition to radiotherapy and their mean survival was 20.0 months. Three of the 14 patients have had an inordinately long disease-free survival of 64, 75, and 80 months from the time of diagnosis.