Two groups of patients with annoying tinnitus were studied with brainstem response audiometry. One group comprised 56 patients with normal hearing or slight hearing loss and another of 57 patients with moderate to pronounced sensorineural hearing loss. The patients were compared with 220 controls matched regarding gender, age, and hearing loss. Two patterns of abnormalities were found. One is a prolongation of wave I accompanied by a prolongation of waves III and V, findings which are consistent with a lesion in the peripheral auditory system. The other is a lengthening of the III-V IPL, indicating a dysfunction in the brainstem. Both patterns occurred most often in tinnitus patients with normal hearing or slight hearing loss.