Background: Undescended testes or cryptorchidism is a developmental condition of abnormal location of testes and they are not normally located in the scrotal sac. It can be unilateral or bilateral. Accurate diagnosis is necessary for healthy fruitful life of male children in future. Ultrasound is being considered the useful imaging tool for the localization of palpable testes. But controversy was noted. Aim: To ascertain the diagnostic accuracy of Ultrasonography for diagnosis of undescended testes in pediatric population using MRI as gold standard Study Design: Cross sectional study. Setting: Department of Diagnostic and Interventional Radiology, Sir Ganga Ram Hospital, Lahore. Duration of Study: 6 months from 09-07-2017 to 10-01-2018 Methods: 130 cases fulfilled inclusion criteria were registered in the study. Patients underwent ultrasonography and later on MRI scan for confirmation of presence of undescended testes. The findings were collected on proforma. Data was entered and evaluated through Statistical Package for Social Sciences (SPSS). Sensitivity, specificity, PPV, NPV and diagnostic accuracy of ultrasound was calculated taking MRI scan as gold standard. Results: The mean age of children was 8.64 +/- 4.08years. The mean weight of children was 30.40 +/- 13.81kg. The sensitivity, specificity, PPV, NPV and diagnostic accuracy of ultrasound were 90.2%, 94.9%, 92%, 93.8% and 93.1% respectively, taking MRI as gold standard. Conclusion: Thus, ultrasound is accurate enough to detect undescended testes. So in future, we can replace MRI with ultrasound for detection of undescended testes and prevent children from hazardous rays of MRI.