OBJECTIVE To compare two different biopsy devices for upper tract urothelial carcinoma (UTUC) and evaluate the pathologic result obtained by these devices. METHODS From January 2008 to December 2010, 414 ureteroscopies were performed and 504 biopsies were taken for evaluation of UTUC. Two biopsy devices were compared: 2.4F stainless steel flat wire basket and 3F cup biopsy forceps. The effect of the biopsy device on obtaining an adequate pathologic specimen was evaluated using univariate and multivariate binary logistic regression analysis. We also investigated whether tumor grade determination was affected by the biopsy device among patients with a diagnostic biopsy. RESULTS Diagnosis was successful in 63% and 94% in the forceps and basket groups, respectively (P < 0.0001). Among biopsies with a definite diagnosis of UTUC, specific grade was determined in 80% and 93% in the forceps and basket groups, respectively (P = 0.033). In subgroup analysis of tumors larger than 10 mm in diameter, diagnosis was obtained in 80% and 94% in the forceps and basket groups, respectively (P = 0.037). Cytologic evaluation was found to increase diagnostic rates. CONCLUSIONS The stainless steel flat wire basket was shown to be superior to the 3F cup biopsy forceps in terms of obtaining tissue diagnosis and providing specific grade.