Although sudden deterioration and death is a widely recognized complication in patients with benign tumors of the third ventricle area, the exact incidence of this dreaded occurrence is unknown and the reports in the literature on the subject are largely anecdotal. Neither risk factors nor the etiology of the sudden death have been analyzed. The vast majority of these benign tumors are colloid cysts, and the presence and degree of ventricular dilatation and herniation associated with these tumors as cited in the reports are quite variable. The authors report a case of sudden death in a 27-year-old woman with a subependymoma of the left lateral and third ventricles. A review of the literature is included in an attempt to discern identifiable risk factors for sudden death in patients with tumors of the third ventricle area. Since this potential complication is known to exist in patients with otherwise benign tumors amenable to surgical resection, the authors recommend either prompt removal of the tumor on discovery or close monitoring of the patient if surgery is to be delayed.