A prospective study examining the incidence of dimercaptosuccinic acid (DMSA) abnormalities in children at the time of acute urinary tract infection, the progression of these abnormalities following treatment and their correlation with the presence of vesicoureteral reflux is reported. DMSA scans performed within 72 hours of presentation in 65 previously healthy children with acute urinary tract infection were abnormal in 34 (52%). The scan appearances of 30 of 36 (83%) initially abnormal kidneys improved or became normal on the repeat DMSA study performed at 3 to 6 months after the acute urinary tract infection. A cystogram demonstrated significant vesicoureteral reflux in 11 of 45 cases (24%). Of these 11 cases 10 had abnormal DMSA studies and 1 had dilated upper tracts on ultrasound. Several conclusions may be drawn from our study. The incidence of DMSA abnormalities at the time of acute urinary tract infection is high but these abnormalities tend to resolve with time. An abnormal DMSA study at the time of urinary tract infection identifies most children with significant vesicoureteral reflux, and in our series a combination of ultrasound and DMSA identified all cases. This study may have major implications for the clinical investigation of children with urinary tract infection.