Stapedotomy is the best way to treat otosclerosis, a progressive, degenerative disease of the temporal bone otic capsule. This paper shows the outcomes of stapedotomy procedures with three different types of prostheses in two time periods. Outcomes were assessed based on the difference in the preoperative and postoperative audiogram. Preoperative and postoperative air-bone gap (ABG), air and bone conduction thresholds were evaluated. The Schuknecht prosthesis was implanted in 66, Richards in 41 and Causse in 75 operations. Schuknecht and Richards prostheses were implanted in 1993-2003 time period, and Causse during 2017-2019. Demographic data show that patients with Causse prostheses are 7-8 years older than patients with Schuknecht and Richards prostheses on average. Also the ratio of women and men with implanted Causse prosthesis is 2:1, while in the other two groups it is 5:1. Patients with Causse prosthesis had higher air conduction thresholds predoperatively compared to the other two groups. The results of pure tone audiometry show that Schuknecht prosthesis is worse than Richards and Causse at all parameters of pure tone audiometry. Richards prosthesis achieves better ABG closure in 250, 500, and 1000 Hz than Causse prosthesis, while Causse prosthesis is better at 4000 Hz. Causse prosthesis also achieved a better reduction of the air conduction threshold than Richards prosthesis at 4, 6, and 8 thousand Hz. The obtained results show that Causse prosthesis achieved the best ratio of good and not so good results in the speech area, although it is not the best at all frequencies individually.