[en] Objective: To investigate the curative effect of transcatheter arterial chemoembolization (TACE) combined with endovascular ¹²⁵I seed strip implantation for the treatment of primary hepatocellular carcinoma (PHC) complicated by extensive portal vein tumor thrombus. Methods: The clinical data of 72 patients with PHC complicated by extensive portal vein tumor thrombus were retrospectively analyzed. The patients were divided into group A (n = 32) and group B (n = 40). TACE combined with endovascular ¹²⁵I seed strip implantation was performed for the patients of group A, while only TACE was employed for the patients of group B. The changes of portal vein tumor thrombus, the survival time and procedure-related adverse events were recorded. The preoperative and postoperative measured values were compared using paired samples t test, the count data were evaluated by χ² test, and the survival time was analyzed with Kaplan-Meier method. Results: Technical success rate of portal vein ¹²⁵I seed strip implantation was 100%. No serious procedure-related adverse events occurred. The median survival periods of group A and group B were 210 days and 141 days respectively, the difference between the two groups was statistically significant (P = 0.012). Conclusion: For the treatment of primary hepatocellular carcinoma complicated by extensive portal vein tumor thrombus, TACE combined with endovascular ¹²⁵I seed strip implantation can significantly improve the patient's survival time. (authors)