There are several insecticidal drugs and agents which induced hearing impairment such as smithion, parathion, rivisite, E.P.N, hosfel, thionex and Bla-S. Recently, untoward side effects of these insecticidal drugs continously increased due to falty handling, suicidal ingestion and direct contact. The author report one case who had irreversible sensorineural deafness after ingestion of Bla-S oil solution for the purpose of suicide.