1. Blood levels were determined in a group of 12 healthy volunteers after single and multiple doses in a four-way cross-over experiment with erythromycin estolate and erythromycin stearate.2. Erythromycin estolate, when administered fasting, is better absorbed than erythromycin stearate.3. Food does not appreciably alter the absorption of erythromycin estolate when the antibiotic is given in single or multiple doses.4. Erythromycin stearate is poorly absorbed when given with food.Comparation del Nivellos Sanguinee de Estolato de Erythromycina e de Stearato de Erythromycina post Administrationes Solitari e Multiple1. In un gruppo de 12 normal voluntarios le concentrationes sanguinee de estolato de erythromycina e de stearato de erythromycina esseva comparate post administrationes solitari e multiple con un piano experimental de cruciamento quadridirectional.2. Estolato de erythromycina, quando administrate in stato jejun, es melio absorbite que stearato de erythromycina.3. Alimento non altera appreciabilemente le absorption de estolato de erythromycina quando le antibiotico es administrate in doses solitari o multiple.4. Stearato de erythromycina es absorbite pauco ben quando illo es administrate con alimento.