Following pyloromyotomy vomiting may persist for several hours or days in a high percentage of children due to a loss of gastric tone. If this is the suspected cause the feedings must be adjusted individually. Other causes for postoperative vomiting are incomplete pyloromyotomy and surgical complications, associated anomalies of the gastrointestinal tract and nonsurgical diseases. A correct diagnosis can usually be made by the assessment of the beginning and the type of vomiting and the other symptoms. To shorten the period of hospitalization is advantageous for decreasing the occurrence of additional diseases.