By means of the staining specific to mucus, namely, by muci-carmine staining of the tubal mucous glands obtained from the guinea pigs previously irradiated with radium, the author studied the changes in these glands. and obtained the following results. 1. When the animals are irradiated with radium in the dose usually used for the treatment of Eustachian-tube catarrh, neither atrophy nor the destruction of the tubal mucous glands can be recognized, but a transient acceleration of the secretory function is elicited. 2. The degrees of destruction of tubal mucous glands and goblet cells by radium irradiation are proportional to the amounts of the irradiation.