Sixty-six newborn infants with urinary tract infection are described. The wide variation in clinical manifestations is stressed and suggested as an explanation for the variety of clinical descriptions, incidence, and prognosis noted by previous authors. The condition commonly presents on the sixth or seventh day, there is no seasonal incidence, boys are affected more frequently than girls. There was a correlation with maternal infection, perinatal anoxia, and birthweight either below or above the normal range. Unsatisfactory weight progress, lethargy, and anorexia were the most frequent clinical signs. The overall mortality was 11% and further infection occurred in 37% of girls and in 10% of the boys. A clinical classification for the condition is suggested.