The benefit of surgery and radiotherapy for patients with low-grade gliomas is controversial. We studied case records of 119 patients diagnosed with low-grade glioma during 1987-1993 at our hospital. Statistical analysis was made on overall survival and on survival related to histological diagnosis and treatment modality. A large variation in survival of patients with similar histological diagnosis was seen. No correlation was found between survival and treatment modality. This clinical diversity probably reflects variations in tumor biological characteristics of low-grade gliomas. Greater understanding of the biology of these tumors will thus be needed for more effective therapies.