We report the first prospective evaluation of middle ear barotrauma in experienced recreational scuba divers. In this pilot study, tympanometric and otoscopic evaluations were performed daily on two experienced scuba divers engaged in multi-day repetitive diving. Middle ear pressures decreased in proportion to diving frequency, demonstrating eustachian tube dysfunction which promptly reversed upon cessation of diving Otoscopic evidence of traumatic injury to the middle ear occurred in proportion to diving frequency, and also readily reversed upon cessation of diving. Tympanic membrane compliance remained normal, often despite pronounced otoscopic abnormalities. Otologic symptoms and impairment of acuity were not observed. Tympanometry appears to be a valuable modality for the verification of middle ear hemorrhage or tympanic membrane rupture. This preliminary data should assist investigators in planning more comprehensive studies of middle ear barotrauma, including clinical trials of treatment and prophylactic interventions for this common condition.