T HE modern concept of the pathologic anatomy of congenital hypertrophic pyloric stenosis stems from the papers of I-Iirsehsprung (1888). I However, at least two reports indicate that the condition was recognized in adults prior to that time (Landerer, 2 1879, and Mater, 3 1885). The earliest known reference to the disease was that by Beardsley whose accurate description of the condition appeared in 1788 in the earliest volume of medical transactions issued in this country entitled, "Cases and Observations by the ~edieal Society o2 New Haven County in the State of Connecticut." Because of widespread interest in this disease, Beardsley's report was later republished. 4 Within the decade following Hirschsprung's report, some twenty case histories were collected from the world literature 5 and by 1902 a total of fifty cases had been recorded, in nineteen of which operation had been performed2 Various operative procedures were described and practiced prior to the turn of the present century. Loreta 7 (1887) performed a divulsion of the pylorus and introduced graduated sounds through an incision in the gastric wall in an attempt to dilate the pyloric canal. Rather than dilating, the stenotic area usually ruptured and produced a uniformly fatal peritonitis. Simple pyloroplasty (Cautley and Dent, 6 1902), consisting of conversion of a longitudinal incision into a transverse one in the manner of the HeinekeMikulicz procedure, was popular for only a short period. The incision extended through the entire pyloric tumor into the stomach and duodenum, and peritonitis again was the most common cause of failure. Gastroenterostomy was a logical procedure in the early surgical treatment of hypertrophic pyloric stenosis because it was a popular choice for treating allied conditions in the adult. Even though diligent efforts resulted in a steadily decreasing mortality rate, it still remained higher than the reasonable rate for abdominal procedures. Research therefore was directed toward the exploration of the various types of pyloroplastics, culminating in the submucous pyloroptasty (Fredet-Rammstedt procedure) which has few peers with respect to its merit and practical results in the annals of surgical practice. The value of extramueous pylorop]asty in the treatment of congenital hypertrophic pyloric stenosis cannot be denied. Pierre Fredet s mus t receive credit for the basic essential of the operation: the longitudinal incision of the serous and muscular layers of the pylorus without in jury to the mucosa. The operation he described in 1908 included the conversion of the longitudinal incision into a transverse one by suturing. Conrad Rammstedt, 9 in 1912, first omitted closure of the incision, allowing the pyloric wound to gape widely without further manipulation. Although this modification is the operation in universal use in modern surgery, both pioneers should receive their due. The Fredet-Rammstedt operation for hypertrophic pyloric stenosis is their monument.