Giant cavernous malformations (GCMs) occur very rarely and little has been reported about their clinical characteristics. The authors present a case of a 20-year-old woman with a GCM. She was referred due to two episodes of generalized seizure. Computed tomography and magnetic resonance image demonstrated a heterogeneous multi-cystic lesion of $7 imes5 imes5$ cm size in the left frontal lobe and basal ganglia, and enhancing vascular structure abutting medial portion of the mass. These fingings suggested a diagnosis of GCM accompanying venous angioma. After left frontal craniotomy, transcortical approach was done. Total removal was accomplished and the postoperative course was uneventful. GCMs do not seem differ clinically, surgically or histopathologically from small cavernous angiomas, but imaging appearance of GCMs may be variable. The clinical, radiological feature and management of GCMs are described based on pertinent literature review.