Objective: Upper urinary tract urothelial cell carcinomas (UUT-UCCs) are rare but usually invasive at diagnosis. Early diagnosis of UUT-UCCs is thus warranted. UUT has the same embryological origin with bladder and BLCA-4 is a highly sensitive and specific marker for bladder cancer. We intend to investigate the viability of BLCA-4 in detecting UUT-UCCs. Material and methods: Urines from 30 UUT-UCC patients, 10 ureteral polyp patients, 20 infected patients with incarcerated ureteral stones, and 30 normal controls were included. BLCA-4 antibody was produced and applied in an indirect ELISA assay. Results: Urinary BLCA-4 is significantly higher in UUT-UCC group than «Polyp» group (P = 0.0017), «Infection» group (P < 0.0001), or « Normal» group (P < 0.0001). The «Polyp» group is also higher than «Infection» group (P = 0.015), or «Normal» group (P = 0.0009). ROC curve revealed at cut-off of 5.5 × 10-4 A, sensitivity was 93.3% and specificity was 100%. When grouped as ureteral mass vs normal, same cut-off value yielded 93.3% sensitivity and 83.3% specificity. At 2.4 × 10-4 A, sensitivity was 56.7% and specificity was 97.2%. Conclusions: Urinary BLCA-4 is also highly specific in UUT-UCCs detection. For incidentally identified ureteral mass, BLCA-4 can be considered an auxiliary indicator besides biopsy. © 2012 AEU. Publicado por Elsevier España, S.L. Todos los derechos reservados.