Assess the changes in Eustachian tube (ET) function (ETF) with balloon dilation of Eustachian tube (BDET). Prospective cohort for repeated testing measures. Clinical research center. Eleven adults with at least one patent ventilation tube (VT) inserted for chronic ET dysfunction (ETD) and history of otitis media with effusion. Subjects with evidence of moderate to severe ETD on the side with a VT underwent unilateral BDET. Changes in ETF parameters after BDET measured by Forced Response Test (FRT), Inflation Deflation Test (IDT), and Pressure Chamber test. With the FRT at 11 ml/min, opening pressure (OP) decreased from 458 ± 160 to 308 ± 173 daPa and closing pressure (CP) from 115 ± 83 to 72 ± 81 daPa at the 3-month post-BDET visit. The IDT and Pressure Chamber test showed that the percentage of middle ear (ME) pressure gradient equilibrated with swallows improved from 28 ± 34 to 53 ± 5% for positive and from 20 ± 28 to 38 ± 43% for negative ME pressure. Images from the pre- and post-BDET functional CT scans did not show apparent changes in the anatomy. Comparisons of ETF test parameters pre- and post-BDET suggested that the ET was easier to open and stayed open longer after the procedure. However, during the limited duration of follow-up most subjects continued to have ETD, some requiring VT re-insertion after the study period. Adults with severe ETD may benefit from BDET, however ETD may not be completely resolved and patients may continue to need VTs.