Background: Tc99m DMSA (dimercaptosuccinic acid) scintigraphy has a high sensitivity for the detection of cortical kidney damage. Aim: To evaluate the Tc99m DMSA renal scintigraphy in children with a first episode of acute pyelonephritis and its association with laboratory parameters, kidney ultrasound and vesicoureteral reflux. Patients and methods: We studied 143 children (age range 8 days, 12 Years, 66% female) hospitalized with the clinical diagnosis of acute pyelonephritis (first episode) with a positive urine culture and a renal scintigraphy performed within seven days of diagnosis. DMSA was considered the gold standard for the detection of cortical lesions. Its results were related to the presence of fever C-reactive protein (CRP), erythrocyte sedimentation rate white blood count (WBC), ultrasound examination and vesicoureteral reflux. Results: Seventy nine percent of the population bad an abnormal DMSA scan. There were no differences between sex, age and laboratory parameters in children with normal or abnormal DMSA scans, except for CRP (p < 0.005). Ultrasound was coincident with the scan in 32% of patients. Eighteen percent bad vesicoureteral reflux. Conclusions: There is a high proportion of abnormal DMSA scans in children with a first episode of acute pyelonephritis (Rev Mid Chile 2004; 132: 58-64).