Background and Objective: This study aimed to assess cochlear functions in Behcet's disease and rheumatoid arthritis (RA) using otoacoustic emission testing (OAE), which objectively assesses outer hair cells in the cochlea. Methods: Patients with Behcet's disease (n = 16) and RA (n = 11) as well as 20 controls were tested using pure tone audiometry and transiently evoked (TEOAEs) and distortion product OAEs (DPOAEs). Results: Pure tone results in the Behcet's group were not significantly different from controls (p > 0.05). Pure tone results in the RA group were significantly different than in controls at 250, 500 and 6,000 Hz (p < 0.05). TEOAEs could be obtained in all participants. DPOAE amplitudes in the RA group and controls were similar (p > 0.05). DPOAE amplitudes were significantly higher in the Behcet's group than in controls at 1 and 2 kHz (p < 0.05). Conclusion: A subtle deterioration in hearing can be seen at low and high frequencies in RA, which is not related to outer hair cell dysfunction as detected by DPOAE testing. In the patients with Behcet's disease who have hearing thresholds within the normal limits, outer hair cell functions seem spared with an increased activity in the apical regions of the cochlea. (C) 2007 S. Karger AG, Basel.