목적: The objective of this study was to obtain functional results after endoscopic type 3 tympanoplasty in Mongolian patients with conductive hearing loss due to chronic otitis media. 방법:In 2020-2023, this study included 120 patients who underwent endoscopic type 3 tympanoplasty, using PORP or TORP for ossicular chain reconstruction (OCR) and cartilage graft for tympanic membrane reconstruction. Of those patients, who following criteria: air conduction is more than 25 dB, air conduction vs bone conduction is more than 15 dB by ENT examinations and hearing test. 결과:Of the total patients, 51 (42.5%) had cholesteatoma, 53 (44.2%) had granuloma, and 16 (13,3%) had middle ear adhesive inflammation. Of the patients with tympanic membrane perforation, 94 (78.3%) had central tympanic membrane perforation, 17 (14.1%) had upper tympanic membrane perforation, and 9 (7.6%) had lower tympanic membrane perforation. By age group, 12.3% were children aged 3-16 years, 87.2% were 17-60 years old. According to detailed audiological examination, air conduction was more than 25 dB, bone-air gap was more than 15 dB, and the average hearing loss was 35.5 dB. According to our study, 45(37.5%) patients had normal ossicular chain, 4(4.1%) patients had immobilized ossicular chain, 15 (12.4%) patients had fractured and fused malleolus, and 35 (29.1%) patients had injury of incus long process, 21 (17.5%) patients had injury of stapes bone. Tympanoplasty III Type PORP in 37(80.4%) of 46 patients, 2.25 mm titanium prosthesis and 2.5 mm titanium prosthesis in 9 (19.6%) placed on the head of the stapes, and in 82% of cases, the hearing improved by 10-25dB. Tympanoplasty III Type TORP 4.0 mm titanium prosthesis was used in 25 patients with stapes injury, and hearing improved by 10-30dB. Of the 120 patients included in the study, 42 (35.1%) of the tympanic membranes were repaired with a perichondrium graft and 78 (64.9%) with a cartilage-perichondrium composite graft. 12.3% of these patients who repaired with perichondrium graft replacement had reperforation. 결론:Hearing improvement the following ossicular chain reconstruction of titan prosthesis was 80%.