Previously, we reported on the changing concepts in the management of 35 neonates with primary obstructive megaureters, 25 of whom were observed without surgery for a mean of 28 months while 10 were surgically treated. We report the long-term outcome of the 25 patients who were managed without surgery. This group consists of 19 male and 6 female neonates with 19 unilateral and 6 bilateral dilated ureters. Of the patients 17 presented with an antenatal diagnosis of hydronephrosis, 2 with infection and 6 with incidental findings. None of the patients had vesicoureteral reflux. Followup serial imaging (2 or more studies per case) consisted of excretory urography in 18 of the 25 cases, diethylenetriaminepentaacetic acid renal scan in 16 and/or sonogram in 10. Mean followup was 7.3 years (range 4.8 to 12.4) for 24 patients and 1 was lost to followup after 1.5 years. Excretory urography showed improvement in urinary tract dilatation in 12 cases and stable dilatation in 6. Renal scans demonstrated expected interval increases in the glomerular filtration rate with age without any deterioration in per cent of renal function in all 16 cases. None of the patients had stones, pain or pyelonephritis. We conclude that it is safe to follow a select group of patients with primary dilated megaureters in the absence of vesicoureteral reflux. We recommend antibiotic prophylaxis and serial urinary tract imaging to confirm renal growth and preservation of renal function.