Practices regarding central nervous system (CNS) prophylaxis and treatment for non-"high-grade" lymphomas are not standardized. We designed a survey to address the CNS surveillance, prophylaxis and treatment (S + P + T) habits of Ontario oncologists, to compare tertiary with community care and gauge interest in a randomized controlled trial (RCT). We mailed 145 questionnaires to oncologists/hematologists registered at the Royal College of Physicians and Surgeons of Ontario between 1980 and 1999. The questionnaire posed questions of S + P + T for a variety of histologies, locations and risk factors. Results showed that 49/77 respondents treated adult NHL, (19 community, 30 tertiary care). Surveillance LP's were commonly done in testicular, orbital, sinus and epidural sites of presentation (76, 69, 71, 80%, respectively), but these were less commonly prophylaxed (45, 33, 29 and 41%). HIV associated NHL received surveillance and prophylaxis by 51 and 33% of respondents. Stage IV disease, increased LDH and extranodal-sites warranted infrequent S + P. IT chemotherapy via LP was the most commonly used form of prophylaxis (74%) or treatment (84%). Twenty percent used systemic agents that cross the blood brain barrier for prophylaxis, and 45% for treatment. A vast heterogeneity of practice within and between tertiary care and community physicians' practices was documented. Ninety percent of physicians indicated willingness to participate in a RCT. In conclusion, CNS surveillance and prophylaxis in non-"high-grade" NHL is highly variable, probably because there are poorly defined risk factors, inconclusive prophylaxis efficacy and the inconvenience/toxicity of therapy. Patients at high risk by International prognostic index criteria are at an increased risk for CNS relapse. A RCT comparing standard chemotherapy with or without CNS prophylaxis in selected patients is needed.