In monitoring patients for drug-induced hearing loss, most audiometric evaluations are limited to the range of frequencies from 0.25 to 8 kHz. However, such testing would fail to detect ototoxicity in patients who have already experienced hearing loss in the ultrahigh frequencies from 10 to 20 kHz. Awareness of ultrahigh-frequency ototoxicity could lead to changes in a drug regimen to prevent further damage. We conducted a prospective study of 105 patients who were receiving a potentially ototoxic drug-either gentamicin, amikacin, or cisplatin-to assess the value of ultrahigh-frequency audiometry in detecting systemic drug-induced hearing loss. We found that expanding audiometry into the ultrahigh-frequency range led to the detection of a substantial number of cases of hearing loss that would have otherwise been missed.