Otitis media with effusion (OME) is a common disease and eustachian tube (ET) dysfunction is widely known to be related to the incidence of OME; however, objective evaluation tools for ET function are lacking. To evaluate ET openings by tubomanometry (TMM) in adult patients with otitis media with effusion (OME), the ET patency of 123 ears, including 63 ears of OME patients and 60 control ears, were tested using TMM and tympanometry. ET patency was evaluated by the R value and ET score, and was compared to the tympanogram results. The eustachian tube dysfunction questionnaire (ETDQ-7) was used to assess the severity of the symptoms in OME patients. The results showed that the rates of restricted opening or blocked ET under pressures of 30, 40, and 50 mbar by TMM testing were 10, 5, and 0 %, respectively (control group) and 76.19, 66.7, and 57.97 %, respectively (OME group) (p < 0.05 for all pressure groups). However, the rates were 77.42, 71.97, and 61.29 % in the type B tympanogram group, and 75, 62.5, and 46.87 % in the type C tympanogram group; no significant difference was found at each testing pressure (p = 0.821, 0.246, and 0.516; respectively) between these tympanogram groups. The mean ETDQ-7 score in OME patients was 16.40 ± 10.72, which was significantly negatively correlated with the ET score at 30 and 40 mbar (30 mbar: correlation coefficient -0.29, p = 0.025; 40 mbar: correlation coefficient -0.28; p = 0.030), but not at 50 mbar (correlation coefficient -0.013, p = 0.924). These findings showed that ET blockage or delayed opening were found in most adult patients with OME when evaluated by this innovative and semi objective TMM, testing pressures should be considered when assessing the results of TMM in OME patients.