ABSTRACT Objective Recent studies have demonstrated the role of systemic inflammation in the development and progression of cancer. In this study, we evaluated whether preoperatively measured neutrophil-to-lymphocyte ratio (NLR) can predict lamina propria invasion in patients with non-muscle-invasive bladder cancer (NMIBC). Material and Methods We reviewed the medical records of 304 consecutive and newly diagnosed patients with bladder cancer who had been treated with transurethral resection between January 2008 and June 2014. In total, 271 patients were included in the study and the patients were divided into two groups according to the pathological stage (Group 1: Ta, Group 2: T1). NLR was calculated by dividing the absolute neutrophil count (N) by the absolute lymphocyte count (L). Results In total, 271 patients (27 women and 244 men) were enrolled. Mean age was higher in Group 2 than in Group 1 (67.3±10.8 vs. 62.9±10.8, p<0.001). Furthermore, the presence of high grade tumors and tumors ≥3cm in size was statistically higher in Group 2 than in Group 1 (70.9% vs. 9.9%, p=0.0001; 71.8% vs. 36%, p=0.0001, respectively). While the mean white blood cell (WBC) and N counts were statistically insignificant (7.63±1.87 vs. 7.69±1.93, p=0.780; 4.72±1.54 vs. 4.46±1.38, p=0.140; respectively), L was significantly lower and NLR was significantly higher in Group 2 than in Group 1 (2.07±0.75 vs. 2.4±0.87, p=0.001; 2.62±1.5 vs. 2.19±1.62, p=0.029; respectively). Conclusion Our data indicate that high NLR and low L are statistically associated with T1 stage, whereas low L are able to predict lamina propria invasion in patients with NMIBC. These findings suggest that pretreatment measurement of NLR may provide valuable information for the clinical management of patients with NMIBC. Prospective studies are now required to further validate the role of NLR as a risk factor in NMIBC.