Instrumentation of the ureters has an incidence of major complications and in a ser:es of 172 patients 3% had a major infection; 1% anuria and 2% perforation of the ureter. That this procedure should be considered selective and not routine is further reflected by a pronounced decrease in its use from 45% to 10% of all activities over an 8-year period in the urological theatre of Johannesburg Hospital. Indications for ureteric catheterization should be definite and contributory.