Since 1988 the Society for Fetal Urology has worked to evaluate if there is consensus on management of infants with nonspecific hydronephrosis. Initially, multicenter agreement on the criteria to grade hydronephrosis and method of diuretic renography were developed to promote similarities in how infant kidneys with nonspecific hydronephrosis were profiled for grade (0 to 4), per cent differential function by diuretic renography and drainage response by diuretic renography (obstructed, not obstructed or indeterminate). Between 1989 and 1992 a total of 33 pediatric urologists from 21 cities registered 464 cases (582 kidneys) of hydronephrosis. Of the cases 275 (59%) were managed by observation and 189 (41%) were treated surgically. The operated kidneys showed profiles (hydronephrosis grade 3 or greater and diuretic renography obstructed) that were significantly different from the profiles of observed kidneys (hydronephrosis grade 2 or less and diuretic renography no obstruction) (p < 0.001 each). Six months postoperatively the mean grade of hydronephrosis (1.8) and diuretic renography diagnosis (no obstruction) were significantly better than they were preoperatively (p < 0.001 each). In addition, postoperatively the mean grade of hydronephrosis, diuretic renography diagnosis and per cent differential function were similar to age matched observed kidneys. We conclude that when radiographic tests are done similarly, there is consensus in the management of infant hydronephrosis by surgery or observation.