Although much remains to be learned, most pediatric nephrologists and urologists are now in comfortable agreement with the following assumptions: (1) Most reflux (primary reflux) is due to a congenital anatomic abnormality of the bladder trigone. (2) In many instances this anomaly improves with growth and development of the child so that the reflux may cease spontaneously. In low-grade (I-II) reflux with undilated ureters, approximately 75 to 85 per cent will stop refluxing. In higher grades (III-V) with dilated ureters, the cessation rate is in the range of only 25-30 per cent. (3) Although radiologic grading is helpful in predicting the likelihood of spontaneous cessation, it is possible to improve that predictability by cystoscopic evaluation of the size, configuration, and position of the ureteral orifice plus the length of the submucosal tunnel. (4) Reflux in combination with bacteriuria can and does lead to renal scarring. (5) Renal scarring probably does not occur in patients with primary reflux and normal voiding pressures in the absence of bacteriuria. (6) Renal growth may proceed normally despite sterile reflux. (7) A few refluxing patients, perhaps 10 per cent, will have bacteriuria despite continuous antimicrobials, and these "breakthrough" infections may cause renal scars. (8) Other patients prove either unwilling or unable to comply with continuous medications and are also vulnerable to scars. (9) A successful antireflux operation may not change the recurrence rate of urinary tract infections per se, but it almost eliminates the likelihood of pyelonephritic episodes and the necessity for further continuous antibiotics. Unfortunately, in patients with intermediate grades of reflux, it is not presently known whether an early surgical correction might be more effective in allowing normal renal growth, in avoiding renal scars, and in preventing eventual hypertension, which is present as a late complication in almost 20 per cent of the patients. The data to answer this important question should ultimately be forthcoming from the current International Collaborative Reflux Study.