Ten neonates and infants with 11 ectopic ureteroceles prospectively underwent transurethral puncture as the primary form of therapy. Of the 10 patients 6 had a prenatal diagnosis of uropathy and 4 presented postnatally with urinary tract infection. One patient had bilateral single system ectopic ureteroceles and 9 had a single ectopic ureterocele in a duplex system. Significant associated ipsilateral and/or contralateral urological pathology was noted in addition to the ectopic ureterocele in 7 patients. Transurethral puncture adequately decompressed 10 of the 11 ectopic ureteroceles (91%) and improved drainage of nonureterocele moieties in 3 cases. Iatrogenic reflux was found in 3 of the 11 ureterocele ureters. Urinary tract infection developed in 6 infants (4 with fever). Of the 10 patients 8 (80%) eventually required secondary surgical intervention because of recurrent urinary tract infections, persistent or iatrogenic reflux, or unresolving hydronephrosis. Although transurethral puncture rarely constitutes definitive treatment for ectopic ureterocele, there appears to be immediate benefit in cases of bilateral hydronephrosis or significant ipsilateral lower pole hydronephrosis. Decompression of the ureterocele is reliably obtained but it seldom obviates the need for more definitive reconstruction.