SOMETIMES an uncommon reaction to a drug will be discovered and reported by a number of observers, and then for a time it will be forgotten and thus go undetected. Later it will be rediscovered and publicized again. This is essentially what has happened in the case of the tetracyclines. Reports of fatty changes in the liver and, ocsionally, jaundice1-7appeared soon after chlortetracycline and oxytetracycline began to be used extensively. Studies on mice, rats, rabbits, and dogs showed that chlortetracycline and, to a lesser extent, oxytetracycline and tetracycline produced fatty metamorphosis and cellular necrobiosis in the liver.8-10Physicians were advised to use no more than 2 gm per day of chlortetracycline or oxytetracycline intravenously or by mouth (or comparable doses for children), and after this no cases were reported. During the next few years tetracycline was developed, and it rapidly became the most frequently used antibiotic in