THE AUTHORS STUDIED 65 patients with intractable seizures and glial tumors who were treated between 1978 and 1991. Most of the tumors were in the temporal (63%) or occipital lobe (18%) and were commonly found in limbic or perilimbic neocortical locations. The majority of these gliomas (83%) involved the gray matter of allocortex, neocortex, or transitional cortex. These tumors spanned a wide range of glial differentiation: Most (61%) were low-grade astrocytomas, but 17% were histologically malignant. However, their biological behavior was strikingly indolent, as suggested by a stable clinical history during many years of chronic seizures (mean, 15 yr). The median follow-up time since the onset of symptoms in these patients was 17.2 years, and only one patient in the entire series died from the tumor. The mainstay of the surgical treatment was resection of the gliomas to histologically confirmed, tumor-free margins. The resection was not guided by intraoperative electrocorticography. Of the 60 patients who had a postoperative follow-up of more than 1 year, 82% were seizure free. Of the 31 patients who had auras with their seizures, 87% did not retain their auras postoperatively. Of the patients who were rendered seizure free, only one patient continued to have auras. Failure in seizure control was associated with an incomplete resection of the lesion. In patients with temporal lobe tumors, seizure outcome was not significantly related to the extent of medial temporal resection. It is suggested that limbic and perilimbic gliomas associated with intractable seizures constitute a distinct clinicopathologic group of glial tumors that involve the gray matter, arise in a young host, and exhibit stable biological behavior over many years. Surgical treatment that includes complete resection of these tumors can achieve excellent seizure control.