DESPITE THEIR UNIQUE clinical, radiological, and surgical considerations, diaphragma sellae meningiomas remain largely undistinguished from tuberculum sellae meningiomas. On the basis of our experience with 12 patients with diaphragma sellae meningiomas and our review of the literature, we classify these tumors into three groups: Type A, originating from the upper leaf of the diaphragma sellae anterior to the pituitary stalk; Type B, originating from the upper leaf of the diaphragma sellae posterior to the pituitary stalk; and Type C, originating from the inferior leaf of the diaphragma sellae. Each type has specific clinical symptoms. Type A mainly presents with unilateral visual disturbances and visual field defects resembling those of tuberculum sellae meningiomas, although preoperative diabetes insipidus occurred in patients with large tumors. Type B causes fewer visual disturbances, but memory disturbance and hypopituitarism occur. Type C closely resembles nonfunctioning pituitary adenomas; bitemporal hemianopsia and hypopituitarism are common. Multiplanar magnetic resonance images can accurately diagnose the tumor and establish its type. Surgical approaches include the cranio-orbital approach for Types A and B and the transcranial-transsphenoidal approach for Type C. Surgery is more difficult than for tuberculum sellae meningiomas because of the deep location and the difficulty of dissecting Types A and B from the pituitary stalk. Repair of the sphenoid sinus to prevent cerebrospinal fluid leakage is mandatory for Type C tumors.