Objective: To analyze function of middle ear on total atelectasis by audiometry and tympanometry. Materials and method: Clinical observations were made on 48 ears from 44 patients who had operated total atelectasis at The Vietnam National Hospital of Otorhinilaryngology from 2010 to 2012. ResulJ: Air bone gap (ABG) on total atelectasis was 28,6 +/- 11,39 dB, ABG at the 4th grade was significantly more than the 2nd grade and 3rd grade with p0,05. The tympanometry presenting in most cases was type B or C, peak of volumne was -168,2 +/- 95,53 daPa. Conclusion: Total atelectasis reflected the negative pressure of middle ear, the fixation of tympanum and ossicular or discontinued ossicular, caused decreasing hearing and ventilation function.