Benign transient hyperphosphatasemia is characterised by high serum alkaline phosphatase levels which is seen early childhood. The etiology is unknown but can be relation many viral infections. The high alkaline phosphatase levels turn normal in 2-6 months. This article presents a patient of 19 months old boy whose levels of alkaline phosphatase were found 3755 UI/L after acut gastroenteritis. The patologies of related bone or liver not found. Later the high alkaline phosphatase levels turn to normal spontaneously in 3 months. ©2008, Firat University, Medical Faculty.