To the best of the author's knowledge, no case of a patient with stapediovestibular ankylosis who was also coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) has been previously described in the literature. This report describes the case of a 36-year-old woman who was diagnosed with all three conditions. The clinical diagnosis of stapes fixation was based on otoscopic, audiometric, tympanometric, and surgical findings. Stapedectomy was performed, and perilymph and serum samples were obtained and tested for anti-HIV and anti-HCV antibodies. While the titers of anti-HCV antibodies in the serum and perilymph were of similar magnitude, there were almost 16 times more anti-HIV antibodies in the serum than in the perilymph. This case offered a unique opportunity to study the titers of anti-HIV/HCV antibodies in both the blood serum and perilymph. Data relating to these titers may provide new insights into the mechanisms of stapediovestibular ankylosis and inner ear immunology.