Diarrhea occurs occasionally in new-born infants. but it is easily controlled with simple measures. Few occurrences have been recorded in the literature of epidemics of diarrhea in new-born infants. During the last three years, however, more than twenty-five such epidemics have occurred in various hospitals in New York City, a fact which led the department of health early in 1936 to call the attention of physicians and lying-in institutions to the condition, urging that all cases be promptly reported to the department of health for investigation.1 A report of the investigations made by the department of health2was presented at the annual session of the American Medical Association in Atlantic City in 1937. We have had the opportunity to follow carefully one of the epidemics that occurred in the nursery for newborn infants of a general hospital in this city and are reporting our results. We shall make