BackgroundTo determine the predictive value of preoperative lymphocyte-to-monocyte ratio (LMR) for pathological and survival outcomes in upper tract urothelial carcinoma (UTUC) after radical nephroureterectomy (RNU). MethodsThis retrospective study included 704 UTUC patients between 2008 and 2017. We used a cutoff LMR of 3.6 to evaluate its relationship with oncological outcomes after RNU, using the Kaplan–Meier method and logistic regression models. ResultsDuring median follow-up of 39 months, decreased preoperative LMR was an independent predictor of poor pathological outcomes. Kaplan–Meier analysis revealed that patients with low LMR (<3.6) had poor cancer-specific survival (CSS), recurrence-free survival (RFS), and overall survival (OS); this prognostic value was ascertained for patients with high pathological grade and more advanced stage UTUC, but not for patients with low pathological features. Multivariate Cox proportional hazards model revealed that low LMR was an independent predictor of poor CSS, RFS and OS [hazard ratio (HR) = 1.42, P = 0.02; HR = 1.39, P = 0.008; HR = 1.38, P = 0.017, respectively]. ConclusionPreoperative low LMR was an independent predictor of poor pathological and oncological outcomes of UTUC after RNU. Subgroup analysis confirmed that the prognostic value of LMR was confined to patients with a high pathological grade and more advanced stage tumor.