Thirty-one patients operated upon for supratentorial glioblastomas or anaplastic astrocytomas were studied to evaluate the effect of the extent of surgical resection on the length and quality of survival. The median age was 50 years and the median preoperative Karnofsky rate was 80. Twenty-one patients (68%) had glioblastoma multiforme, and 10 patients (32%) had anaplastic astrocytoma. Early postoperative enhanced computed tomography was used to determine the extent of tumor resection. Gross total tumor resection was accomplished in 19 patients (61%), and subtotal resection was performed in 12 patients (39%). The two groups were comparable regarding age, sex, pathological condition, preoperative Karnofsky rating, tumor location, postoperative radiation therapy, and postoperative chemotherapy (P greater than 0.05). The gross total resection group lived longer than the subtotal resection group by life table analysis (P less than 0.001; median survival of 90 and 43 weeks, respectively). Postoperatively, the mean functional ability measured by the Karnofsky rating was significantly increased in the gross total resection group (P = 0.006), but not in the subtotal resection group (P greater than 0.05). The difference in degree of change between preoperative and postoperative Karnofsky rating in the two groups was statistically significant (P = 0.002). The gross total resection group spent significantly more time after the operation in an independent status (Karnofsky rating greater than or equal to 80) compared to the subtotal resection group (P = 0.007; median time of 185 and 12.5 weeks, respectively). Gross total resection of supratentorial glioblastomas and anaplastic astrocytomas is feasible and is directly associated with longer and better survival when compared to subtotal resection.