Data from 55 consecutive patients with low-grade astrocytomas treated between 1982 and 1990 were analyzed to determine specific outcome factors, including time to recurrence, incidence of anaplastic transformation, and survival. Gender, type of symptoms, contrast enhancement, and timing of radiation therapy were not significant in determining outcome. Patients who had symptoms for > 2 years and underwent gross-total resection of the tumor, with age as a continuous variable, were associated with significantly longer time to recurrence and survival. Within the population of patients with low-grade astrocytomas, patients with chronic epilepsy clearly had the best prognoses. There were no tumor recurrences or deaths in 27 patients with chronic epilepsy, regardless of the extent of surgery and without the use of radiotherapy. Ten-year survival was 100% for 31 patients who underwent gross-total tumor resection, regardless of the length of preoperative symptoms. Immediate postoperative radiotherapy did not prolong the time to recurrence, reduce the incidence of transition to more malignant tumors at recurrence, or increase the length of survival when compared with delayed radiotherapy. Because recurrence with a high-grade lesion caused 92% of the mortality in our series, the benefit in patients who underwent aggressive surgery seems to result from a significant decrease in the risk of recurrence when compared with patients who underwent anything less than gross-total resection. Our data also suggest that variability in the natural history of low-grade astrocytomas has a strong influence in determining survival and that tumors associated with chronic epilepsy are much less likely to become more malignant over time.