PURPOSE: Recent studies have shown that magnetic resonance arteriography/venography is a highly sensitive tool to identify impalpable testes in young boys. Due to this and the low risk of cancer in testicular nubbins observation has been proposed after the identification of nubbins by magnetic resonance arteriography/venography. We prospectively examined the accuracy of magnetic resonance imaging and magnetic resonance imaging with magnetic resonance arteriography/venography for identifying impalpable testes in a younger cohort of patients typically seen at a pediatric institution in the United States. MATERIALS AND METHODS: We prospectively studied 26 infants and boys with impalpable testes. Conventional magnetic resonance imaging or magnetic resonance imaging with magnetic resonance arteriography/venography was performed in all patients. All patients subsequently underwent surgical exploration. Surgical and radiological findings were then evaluated for concordance. RESULTS: A total of 26 boys (29 impalpable testes) with a median age of 13 months were evaluated. A subset of 14 boys (14 impalpable testes) also underwent magnetic resonance arteriography/venography. Standard magnetic resonance imaging correctly identified 10 of 12 intra-abdominal testes, 4 of 6 intracanalicular testes, 4 of 10 testicular nubbins and 0 of 1 scrotal testis. Magnetic resonance arteriography/venography correctly identified 4 of 5 intra-abdominal testes, 2 of 3 intracanalicular testes, 2 of 5 testicular nubbins and 0 of 1 scrotal testis. The overall accuracy of magnetic resonance imaging alone and magnetic resonance arteriography/venography for identifying a viable testis or testicular nubbin was 62% and 57%, respectively. The accuracy of magnetic resonance imaging and magnetic resonance arteriography/venography for identifying a viable testis was 74% and 67%, respectively. CONCLUSIONS: Preoperative magnetic resonance imaging or magnetic resonance arteriography/venography does not accurately identify or localize impalpable testes in the age group typically presenting to pediatric urologists. Accuracy at our institution is discrepant with that in previous studies. We do not recommend using magnetic resonance imaging or magnetic resonance arteriography/venography for the possible observation of vanishing testes or nubbins and we recommend surgical exploration in all individuals.