This study was undertaken to determine if epinephrine administered endotracheally is as effective in treating anaphylactic shock as is intravenously administered epinephrine. An animal model of anaphylactic shock was produced in anesthetized dogs by the intravenous administration of histamine phosphate. Both the endotracheal and intravenous routes of epinephrine administration resulted in efficient and effective reversal of histamine-induced hypotension. At the doses employed, the intravenous administration of epinephrine resulted in the production of significantly (p less than 0.05) greater numbers of ventricular cardiac arrhythmias than did the endotracheal route of administration.