Of 33 infants with pelviureteric obstruction, most presented in the first month of life with an abdominal mass and most were males. Half of these patients had bilateral renal pathology. The association between cystic dysplasia in the hydronephrotic kidney and contralateral cystic renal abnormality in patients with unilateral pelviureteric obstruction is noted. There were 34 pyeloureteroplasties performed on 27 patients, mostly with good results, even in patients with bilateral renal pathology.