Objectives: Glutathione S-transferase (GST) isoenzymes play important roles in resistance to cell apoptosisand carcinogenesis. We aimed to establish the relationship between GST expression and the prognosis of upperurinary tract urothelial carcinoma (UTT-UC) in Taiwan. Methods: This study retrospectively reviewed 46patients with pathologically confirmed UUT-UC at Kaohsiung Medical University Hospital. In each patient,expression of GSTT1 and GSTP1 was compared between urothelial carcinoma and normal urothelial cells byWestern blotting. Results: GSTP1 expression in the UUT-UC cells was significantly higher than that in normalurothelial cells (1.6 fold, p<0.001). Expression of GSTT1 was significantly associated with the invasiveness ofthe carcinoma (p=0.006). Conclusions: In UUT-UC, GSTP1 might be a potential tumor marker, whereas highGSTT1 expression could be used as an indicator of cancer progression. This study is the first to demonstratepotential applications of different GST isoenzymes for biomolecular analysis of UUT-UCs in Taiwan.