In the literature, many articles have reported on the results of different ossicular reconstruction techniques. These results depend not only on the quality of the prostheses and the technique used, but also on environmental factors. In this work, we describe the results of a study of 67 ossiculoplasties performed in the ENT department of the 20 August 1953 University Hospital in Casablanca, which enabled us to determine the influence of each risk factor and the usefulness of calculating the MER INDEX in predicting the success of an ossiculoplasty, whatever the material used.