To complete their two previous data processing studies on systematization of parameters for otospongiosis and on statistics concerning the otospongiotic disease itself, the authors now develop the study of postoperative functional results obtained over 15 years stapectomies performed according to various techniques. The characteristic of this study is that the functional results are not considered only from the operative technique point of view, but that they also take into account all the factors having an influence upon the functional results, i.e. mechanical operative factors, otospongiotic cochlear factors and, finally the patient's general factor. This work is divided in three parts. The first part considers statistical data drawn from investigating elements taken over a period ranging from 1960 to 1975 from operative findings, surgical techniques and operative complications, particularly during reoperations, i.e., the mechanical part of hearing improvement in otospongiosis surgery. The second part deals with the problem of the medical postoperative care in stapedial surgery and with that of postoperative complications and the therapy used to combat them. It is the study of the cochlear support problem considering both the cochlear fragility facing the operative trauma, and the cochlear deterioration due to the enzymatic action of the otospongiotic microfoci of the lateral wall of the cochlear duct and of the vestibular side of the footplate. The third part is the statistical study made both by means of data processing and of manual investigation, on the long term functional results obtained, on one hand by the surgical solution of the stapedial fixation's mechanical problem, and on the other, by the medical solution of the cochlear problem considered both from the enzymatic and vascular point of view. This study of stapedectomies' long term functional results allows the authors to draw the conclusions which seem to result logically from this very elaborated statistical study concerning near 17000 stapedectomies performed from 1960 through 1975.