Sildenafil is widely administered for the treatment of erectile dysfunction. Recently, sensorineural hearing loss following the ingestion of sildenafil was reported in one male patient. We examined hearing in mice that were administered high doses of sildenafil for up to 105 d. To assess hearing impairment, we evaluated auditory brainstem responses, auditory middle latency responses, and otoacoustic emissions. At high doses, sildenafil increased the hearing threshold shift of auditory brainstem responses. High-dose sildenafil treatment also resulted in delayed latency of both auditory brainstem responses and auditory middle responses. Otoacoustic emissions differed between control and high-dose sildenafil groups with long-term treatment. Collectively, these data demonstrate that high-dose and long-term sildenafil administration can induce hearing impairment in mice.