The available picturing methods in the diagnosis of functional and mechanical stenosis of the lacrimal drainage system do not allow direct optical evaluation of the mucosa. With the help of dacryoendoscopy, for the first time there is the possibility of receiving a direct morphological picture of the tissue of the lacrimal drainage system.In a clinical study in the period January to June 1996, 76 dacryoendoscopies were done before an operative intervention in the lacrimal drainage system to find out what information can be obtained with dacryoendoscopy and what use this extra information is.In all of the dacryoendoscopies performed, direct evaluation of the mucosa was possible. Normal findings could be clearly differentiated from mucosa of acute or chronical inflammatory processes. The choice of the operative strategy changed in part of the planned operations, although in 37 cases where the preoperative diagnosis was stenosis of the lacrimal sac, only in 26 cases was dacryocystorhinostomy performed. Dacryoendoscopy provides an additional means of guaranteeing the quality of operative procedures, e.g., after intubation.Dacryoendoscopy provides an important additional diagnostic possibility in the diagnosis of diseases of the lacrimal drainage system. Dacryoendoscopy offers the possibility of direct evaluation of the mucosa, the choice of operative strategy is checked and, if necessary, changed, and with the connection of an erbium YAG Laser there is minimal invasive surgery with the aim of rechannelization of the lacrimal drainage system.