To assess the prognostic impact of pretreatment albumin-to-alkaline phosphatase ratio (AAPR) in patients with upper tract urothelial carcinoma (UTUC), the data of 692 patients, operated between 2003 and 2016 in our center, were retrospectively assessed. The threshold of AAPR was defined as 0.58 by using the receiver-operating curve analysis. Overall survival (OS), cancer-specific survival (CSS), and recurrence-free survival (RFS) were evaluated using the Kaplan-Meier method. And the univariate and multivariate Cox's regression models were performed to identify independent prognostic predictors. The results showed that AAPR <0.58 was significantly related to higher pT stage and grade, concomitant variant histology, anemia and larger tumor size. Additionally, patients with a lower AAPR had an inferior survival outcomes than those with an AAPR ≥0.58 (all P < 0.001). Multivariate analysis suggested that the lower AAPR was also an independent risk factor for poor OS (HR 1.587, 95%CI: 1.185-2.126; P = 0.002), CSS (HR 1.746, 95%CI: 1.249-2.440; P = 0.001), and RFS (HR 1.337, 95%CI: 1.027-1.739; P = 0.031). Moreover, subgroup analysis demonstrated the lower AAPR was related to worse prognosis in high-grade UTUC patients; but in those with low-grade disease, no relationship between them was observed. In conclusion, our results found that the decreased AAPR was independently related to poor survival outcomes in UTUC patients. Using the AAPR for subclassification of high-grade UTUC seems to further identify a poor prognostic group and contribute to clinical decisions making.