RECENT MEDICAL LITERATURE has stressed the need for a campaign of public education regarding the importance of universal immunization with tetanus toxoid with booster follow-up. This has been stressed because of the increasing severity and frequency of reactions to tetanus antitoxin. It is estimated that from 15% to 30% of persons suffer serum sickness following administration of horse serum and that over 2 million doses of antitoxin are administered annually in this country.1 It is the purpose of this paper to report and document a case of acute myocardial infarction following serum sickness caused by tetanus antitoxin. Report of a Case A 38-year-old white male was admitted to Nassau Hospital, Mineola, NY, on June 8, 1959, with the chief complaint of severe recurring substernal pain accompanied by vomiting. The patient was well until five days prior to admission when he suffered a laceration on the dorsum of his right