Annular pancreas (AP) is a rare congenital anomaly due to malrotation of the pancreatic ventral yolk. Although it has been described in young and middle age adults it predominates in children. Its clinical picture is that of duodenal obstruction or acute pancreatitis episodes. In this paper we report four cases of AP that were seen at the Instituto Nacional de la Nutricion Salvador Zubiran in Mexico City. Three were females and three were less than twenty years old. In one case the diagnosis was established at birth and the operation done in another hospital. In another patient a diagnosis of pyloric hypertrophy was made and a pyloroplasty was performed. This young man was admitted in our hospital because of abdominal pain and hyperamylasemia. An eighty four year old woman was seen due to abdominal pain, nausea and vomit. In all cases the diagnosis of AP was carried out with radiological studies and confirmed by laparotomy. Surgical procedures consisted of duodenal-duodenal anastomosis in two, sphincteroplasty in one, and gastrojejunoanastomosis in the other. Two patients are asymptomatic, one died in the postoperative period, and one was lost for follow up. These four cases represent all the experience of our institute and correspond to one case in 36,735 admissions.