The conditions for the success of surgical interventions within the chiasmal region are careful preparation of the patient, ideal general anesthesia, precise surgical technique especially improved by the use of the microscope and bipolar coagulation. The surgical results also depend on the age of the patient, on his general condition, on the volume of the tumoral lesion and on the extent and kind of implication of the vascular and nervous structures of this region. The lesions are classified into extraparenchymatous lesions, intraparenchymatous lesions, giant aneurysms and inflammatory lesions. The extensive extraparenchymatous lesions represent the most important group: they comprise the pituitary adenomas, the cranio-pharyngiomas, the meningiomas and finally rarer tumors like the chordomas, or other tumors of the sphenoid. In these regions the choice of access is extremely important: transphenoidal, subfrontal intracranial or mixed. Among the intraparenchymatous lesions one has to mention first of all the gliomas of the chiasm and then the ectopic pinealomas. The giant aneurysm in older persons is improved the symptomatology by ligation of the internal carotid. The inflammatory arachnoidal lesions of the chiasm (specific or nonspecific) generally profit from an intervention aiming to disconnect the adhesions. X-ray therapy represents very often an indispensable component of the surgical treatment of the tumoral lesions. Apart from death the complications are postoperative infection, aggravation of the neuro-ophthalmological symptoms, the neuro-psychological consequences and the endocrinological and hypothalamic complications. Early diagnosis represents the best means to diminish the importance of the complications. An alternative complication is the tumor recurrence.