PURPOSE To investigate the proper diagnostic modalities and failure cases of treatment in patients with single-system ectopic ureter (SSEU) who underwent nephrectomy for incontinence. METHODS SSEU combined with dysplastic kidney is a rare cause of female incontinence. We retrospectively analyzed 45 pediatric SSEU patients that underwent simple nephrectomy at our institution during 1996-2013 for incontinence. We reviewed imaging studies to detect dysplastic kidney and ectopic ureter insertion, postoperative results, and urodynamic findings for remaining incontinence after nephrectomy. RESULTS Median operative age was 59.3months. Both ultrasonography and magnetic resonance imaging (MRI) showed 50.0% dysplastic kidney detection rates respectively. Dimercaptosuccinic acid (DMSA) scanning and computerized tomography (CT) showed equal detection rates of 95.5%. Ectopic ureter insertion sites were determined by ultrasonography, CT, and MRI in 17.5%, 13.6%, and 33.3% of patients, respectively. Renal vascular structures were identified in 3/22 patients (13.6%) with CT. Post-nephrectomy, incontinence disappeared in 41 patients (91.1%), but remained in 4 patients (8.9%); urodynamics suggested bladder neck incompetence in these patients. CONCLUSIONS DMSA is a highly sensitive diagnostic modality for detecting dysplastic kidney in SSEU patients with more than 95% detection rates. Once detected by DMSA, additional CT or MRI studies do not provide further information about ectopic ureter insertion or renal vascular structure. Although nephrectomy is successful in nearly 90% of SSEU patients with dysplastic kidneys, postoperative incontinence occasionally remains and requires additional treatment.