AIM To investigate whether the preoperative neutrophil-tolymphocyte ratio (NLR) could predict the prognosis of hepatocellular carcinoma (HCC) patients with portal/hepatic vein tumor thrombosis (PVTT/HVTT) after hepatectomy. METHODS The study population included 81 HCC patients who underwent hepatectomy and were diagnosed with PVTT/HVTT based on pathological examination. The demographics, laboratory analyses, and histopathology data were analyzed. RESULTS Overall survival (OS) and disease-free survival (DFS) were determined in the patients with a high (> 2.9) and low (<= 2.9) NLR. The median OS and DFS duration in the high NLR group were significantly shorter than those in the low NLR group (OS: 6.2 mo vs 15.7 mo, respectively, P = 0.007; DFS: 2.2 mo vs 3.7 mo, respectively, P = 0.039). An NLR > 2.9 was identified as an independent predictor of a poor prognosis of OS (P = 0.034, HR = 1.866; 95% CI: 1.048-3.322) in uni-and multivariate analyses. Moreover, there was a significantly positive correlation between the NLR and the Child-Pugh score (r = 0.276, P = 0.015) and the maximum diameter of the tumor (r = 0.435, P < 0.001). Additionally, the NLR could enhance the prognostic predictive power of the CLIP score for DFS in these patients. CONCLUSION The preoperative NLR is a prognostic predictor after hepatectomy for HCC patients with PVTT/HVTT. NLR > 2.9 indicates poorer OS and DFS.