One hundred seventy-nine adult patients with supratentorial low-grade astrocytomas were treated during a 10-year period. Retrospectively, a series of nine factors were evaluated with simple and multivariate analysis to determine their importance in predicting length of survival. Four appear highly significant (P < 0.005): age, preoperative Karnofsky Performance Scale score, histological grade, and type of surgical removal. Eighty percent of patients with total removal were alive at 5 years compared with 50% with incomplete surgery and 45% with biopsy. For the group under study, the mean time for recurrence was 52 months. For patients surviving for more than 1 year, the chance of being recurrence free went from 75% at 3 years to 25% at 10 years. Among the entire population, the influence of radiotherapy was not obvious: 65% of patients were alive at 5 years without radiotherapy compared with 55% with radiotherapy. A significant difference appeared only for patients older than 40, with incomplete removal (P < 0.05); this difference did not apply to younger patients. The need for postoperative radiotherapy in all patients with subtotal removal, irrespective of their age, has not been demonstrated by this study.