Although transcatheter arterial chemoembolization (TACE) is the most common treatment option in patients with hepatocellular carcinoma (HCC), its clinical benefits remain still controversial. Since TACE induces hypoxic necrosis in tumors, hypoxia-inducible factor 1α (HIF-1α) could critically affect biology in residual tumors after TACE treatment and subsequent prognosis. However, HIF-1α and its prognostic relevance in TACE have rarely been examined in human specimens. In the current study, we investigated the prognosis and expression of genes regulated by HIF-1α in HCC patients receiving preoperative TACE for the first time. In total, 35 patients with HCC (10 patients undergoing preoperative TACE) were retrospectively studied. The prognostic significance of TACE was analyzed using Kaplan-Meier and Cox regression models. Protein levels of HIF-1α and mRNA levels of HIF-1α –associated genes were examined using immunohistochemistry (IHC) and real-time RT-PCR, respectively. Preoperative TACE was significantly associated with increased 2-year recurrence rate (80 vs. 36%, P=0.00402) and shorter disease-free survival (DFS) time (11.9 vs. 35.7 months, p=0.0182). TACE was an independent prognostic factor for recurrence (p=0.007) and poor DFS (p=0.010) in a multivariate analysis. Immunohistochemical staining revealed in vivo activation of HIF-1α in human specimens treated with TACE. Notably, protein levels of HIF-1α were significantly increased in TACE tissues demonstrated by IHC. Transcriptional targets of HIF-1α showed mRNA expression patterns consistent with activation of HIF-1α in TACE tissues. Our findings collectively demonstrate that preoperative TACE confers poor prognosis in HCC patients through activation of HIF-1α.