An electrogustometric study was done to the 25 patients of chronic suppurative otitis media who were admitted for middle ear surgery and to the 20 normal persons as a control group. The study was done about the following aspects : 1) Relation between the duration of the disease and the threshold of EGM. 2) Difference in the threshold of EGM between cholesteatomatous patients and non-choles teatomatous patients. 3) Relation between the degrees of hearing loss and the EGM threshold. 4) Changes of EGM threshold after injury to the chorda tympani. The following results were obtained : 1) The EGM threshold of the control group was markedly increased as age increased. 2) The mean value of the EGM threshold of the control group was 53μA. 3) EGM threshold was high when duration of disease was long. 4) Average threshold in non-cholesteatomatous patients was 61μA and that of cholesteatomatous patients was 80μA. 5) Degrees of hearing loss and EGM threshold had no specific relation, but in moderate severe hearing loss (56~70 dB), the EGM threshold showed highest value, 102μA. 6) After chorda tympani was cut, the EGM threshold increased to 254μA abruptly and there was no recovery.