In August 1937 my associates and I began to use sulfanilamide in the treatment of trachoma at the Rosebud Indian Hospital. For the experiment we selected two patients whose condition had been diagnosed as trachoma by an eye specialist in the Indian Service and by several other physicians in the Indian Service who are especially experienced with trachoma. One of the two patients had had trachoma for two years, the other for eighteen months. Both patients had had grattage, followed by treatments with silver nitrate given intermittently during the period of their infection, with no noticeable improvement. On the basis of their body weight they were given one-third grain (0.02 Gm.) of sulfanilamide, with an equal amount of sodium bicarbonate, a pound daily for ten days. Then the dose was decreased to one-fourth grain (0.016 Gm.) of sulfanilamide a pound daily for fourteen days. No other medication was allowed during