From April to September 1992, systematic screening for iatrogenic vesicoureteric reflux was performed in a series of 30 patients treated by rigid ureterorenoscopy. Most of these endoscopies were performed for renal stones using a Wolff Multiscope (7.5/12 F) without prior dilatation of the urinary tract. The study protocol was essentially based on pre- and postoperative retrograde and voiding cystography. The site and tone of the ureteric orifice and the compliance of the intramural ureter were also evaluated and the operating time was determined. Out of 33 ureteric endoscopies, only one case of type I pelvic vesicoureteric reflux was demonstrated following an operation with no particular technical problems. This rare and benign deferred complication draws attention to the potential consequences of rigid ureterorenoscopy on the vesicoureteric antireflux device.