Intramuscular injections of depot drugs are sometimes followed by a few nonallergic reactions. Usually these are embolic toxic reactions, known as the Hoigné syndrome, following the application of depot procaine penicillin. Psychopathological symptoms predominate in such cases. The Hoigné syndrome that follows application of procaine penicillin is different to that following benzathine penicillin: lung embolism symptoms remain far in the background in the former case but are the dominant symptoms in the latter. The risk of death is slight in the case of the Hoigné syndrome following procaine penicillin application, but it definitely exists. There are probably many slight and misidentified forms of the Hoigné syndrome induced by procaine penicillin. So far, in 7 cases of Hoigné syndrome, we have observed that the syndrome is followed by certain psychopathological symptoms that we wish to call the Styx syndrome.