The transsphenoidal route is the most widely used technique for pituitary adenoma surgery due to its rapidity, good tolerance, effectiveness and low complication rate. These are the parameters we utilized in comparing endoscopic with microscopic transsphenoidal surgery. We reviewed the medical records of 418 patients affected by pituitary adenomas who underwent endoscopic transsphenoidal surgery between May 1998 and December 2004, and in this paper, we present the results of 381 patients who fulfilled the follow-up criteria after a minimum period of 15 months. Our experience confirms the previous data on the rapidity and satisfactory tolerance of the endoscopic procedure. We also confirm the low complication rate, specifying that complications characteristic of the approaching phase were certainly reduced; instead, complications characteristic of tumor removal still remained similar to those reported in the microsurgical literature. The results were comparable with those of the best microsurgical series regarding endosellar lesions, but tumor removal was notably superior when dealing with tumors having an extrasellar extension. The improvement may be explained by the excellent vision of the deep surgical fields due to the endoscope and by the extreme flexibility of the surgical trajectory, mainly due to the absence of the divaricator, giving access to the ramifications of the tumor, otherwise difficult to reach.