OBJECTIVE: We analyzed endoluminal ultrasonography (ELUS) for evaluating renal pelvic and ureteral, or upper tract, urothelial carcinoma (UTUC). METHODS: Patients being treated for suspected UTUC underwent ureteroscopic evaluation immediately before ELUS, followed by ureteroscopic biopsy. Endoluminal ultrasonography was performed using mechanical radial scanning at 30 MHz in the B-mode using a 1.7-mm-diameter (5F) probe, which allows placement over a guide wire. Where possible, ELUS findings at the time of endoscopy were compared to the pathologic findings of resected specimens. RESULTS: From July 2008 to March 2009, 15 patients underwent ELUS during ureteroscopic evaluation of suspected UTUC. No complications occurred as a result of ELUS. Ultrasonographic and endoscopic imaging findings from the evaluation of normal and abnormal anatomy were shown. Eleven patients had evaluable data. Seven patients underwent initial nephroureterectomy. Six of the 7 patients had accurate ELUS staging when correlated with the pathologic findings. The positive predictive value of ELUS was 66.7%, and the negative predictive value was 100%. CONCLUSIONS: In this study, we showed the potential role of ELUS in improving the clinical staging accuracy of UTUC. Although the number of patients was too small to allow for definitive conclusions, these promising initial data suggest that, with additional experience, this modality can substantially improve the risk stratification of patients with UTUC.