Summary:An interaction of bile with erythromycin lactobionatein vitrohas been demonstrated. The major bile components involved in this interaction have been shown to be the bile salts. The nature of the bile salt‐erythromycin interaction has been investigated.The way in which an interaction between bile salts and erythromycinin vivomight lead to the hepatic dysfunction and cholestasis associated with some instances of erythromycin therapy is discusse