In the early period after chronic ear surgery, the reasons for conductive hearing loss may be difficult to determine. Patients who cannot autoinflate the middle ear after 3 weeks, or who have a negative Rinne test result with the 512 Hz tuning fork, are treated with a transtympanic injection of 0.5 cc of air with a 27-gauge needle and tuberculin syringe. This represents 20% of patients who had chronic ear surgery. Results show that hearing may be immediately improved, the sensation of pressure in the ear may be reduced, and fluid may be cleared from the middle ear. Other benefits may include the release of adhesions. The surgeon is better able to assess the thickness of the graft, and the status of the ossicular chain reconstruction can be determined. There have been no complications of middle ear infection or failure of the micropuncture site to heal. In our practice, middle ear air injection is a routine procedure in patients with inadequate eustachian tube function after chronic ear surgery. This report describes the results of 100 patients over 14 years who received middle ear air injections after chronic ear surgery compared with a control group of 100 patients who did not meet the criteria for requiring air injection. Hearing was immediately improved in 74% of patients as determined by Rinne testing. Audiograms were performed in 25 of these patients, documenting a mean improvement in pure-tone average of 16 dB. The long-term hearing results in patients undergoing air injection, who by definition had evidence of poor eustachian tube function, are similar to the results in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)