In the last decade, management of congenital UPJ obstruction has become progressively observational for low grades infants despite the lack of clear dependent predictors of outcome. Furthermore, Surgical intervention for the young infant with high grades, under 6 months, has become relatively infrequent, yet can be necessary and poses unique challenges. In another hand, a careful evaluation and discussion with the family must be undertaken to identify the most appropriate treatment strategy. This review will address the clinical evaluation of UPJO in the very young infant and approaches to determining in whom surgical intervention may be preferable, as well as surgical considerations for the small infant.