A 15 day old baby was admitted with a four day history of increasing vomiting and abdominal distension. After a normal pregnancy and birth he had been admitted to this hospital's special care baby unit for one day because of tachypnoea, grunting, and poor feeding. He had been circumcised by a local community rabbi at 11 days of age. Increasing vomiting and abdominal distension were subsequently noted, but he continued to feed well. His mother thought that he was passing urine normally.