THE MEDICAL profession of the United States has been the most conservative in the world in accepting new vaccines, new drugs, or, in fact, any advance which has not been proved in this country, and particularly by members of the profession themselves. I recall quite vividly, when I was still young in the practice of pediatrics, that two of the leading pediatricians of that time were most reluctant to accept diphtheria toxoid. Smallpox vaccination was not universally accepted until the turn of the century, although it had had more than one hundred years of trial at that time. I am, therefore, not surprised that BCG is having its difficulties in being accepted in the United States. REVIEW OF EXPERIMENTS The first experiment in this country was begun in New York city by Park, Kereszturi and Mishulow in 1926. 1 They reported that by vaccinating children in tuberculous families, they were