Forty-three patients with intracranial, intradural dermoid (8) and epidermoid (35) tumors underwent radical surgical resection utilizing strict microneurosurgical technique. The average age was 37.3 years for the patients with epidermoid tumors and 36.2 years for the patients with dermoid tumors. The male to female ratio was 3:2 for the epidermoid group and 3:1 for the dermoid group. Common clinical presentations included cerebellar dysfunction, cranial nerve impairment, and seizures. Typically, computed tomography scans revealed the epidermoid tumors (30 cases studied) as nonhomogeneous hypodense lesions with irregular borders and without contrast enhancement. The dermoid tumors (7 cases studied) had a similar appearance, but with a wider range of attenuation values. Magnetic resonance imaging findings for the epidermoid tumors (6 cases studied) consisted of increased T1 and increased T2 relaxation times. Supratentorial tumors were excised by the pterional (frontosphenotemporal) approach, mesencephalic tumors by either a supratentorial posterior interhemispheric transtentorial approach or an infratentorial/supracerebellar method, and posterior fossa tumors by either a medially or laterally positioned suboccipital osteoplastic craniotomy. One epidermoid tumor and one dermoid tumor were considered to be subtotally resected because of dense adherences left attached to vital structures; the remaining 41 tumors were completely excised. The most frequent complications were aseptic/chemical meningitis and transient cranial nerve palsies. There were no perioperative deaths. Mean follow-up was 5.2 years. Eighty-six percent of patients reported good to excellent results. No patient had experienced symptomatic or radiographic evidence of recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)