ObjectiveThe study aimed to evaluate the effect of systemic cisplatin administration on off-frequency masking audiometry.MethodsAmong 26 patients receiving systemic cisplatin, 48 ears were included in the analysis. All patients underwent pure-tone audiometry with ipsilateral narrow-band masking noise (off-frequency masking audiometry). In the off-frequency masking audiometry, 70 dBHL band-pass noise (center frequency 1000 Hz, 1/3 octave bandwidth) was administered to the tested ear. The acquired thresholds were compared to those of standard pure-tone audiometry, and threshold elevations greater than 10 dB were regarded as significant. The number of patients showing abnormal threshold elevation was compared between before and after the cisplatin administration.ResultsBefore cisplatin administration, 91.7, 93.8, 97.9, and 93.8% of ears showed normal off-frequency masking audiometry outcomes at 125, 250, 6000, and 8000 Hz, respectively. After cisplatin administration, a higher number of patients showed abnormal off-frequency masking audiometry outcomes. This change was more prominent with increasing doses of cisplatin. After the cisplatin administration of 100∼200 mg/m2, the prevalence of patients with normal off-frequency masking audiometry outcomes was 77.3, 70.5, 90.9, and 88.6% at 125, 250, 6000, and 8000 Hz, respectively. At 250 Hz, the change was statistically significant (p = 0.01, chi-squared test).