Despite improvement of surgical treatment and application of multi-modality therapies to advanced esophageal cancer, the prognosis is extremely poor in patients with T4 tumors. Based on the genetic background of esophageal cancer, we have developed various gene therapy strategies against human esophageal cancer cells. In this article, we reviewed molecular events of esophageal cancer and gene therapy approaches for its treatment. First, we analyzed p53 genetic alterations and angiogenesis in esophageal cancer. Second, we evaluated an impact of p53 recombinant adenoviral vector (Ad5CMV-p53) on esophageal cancer cells. Significant growth suppression was observed following infection with Ad5CMV-p53 in human esophageal squamous cell carcinoma cell lines. This observation suggests that Ad5CMV-p53 may be a potentially effective therapeutic agent for locally advanced esophageal cancer. Promising avenues for investigation include double gene therapy and adjuvant use of gene therapy with radiation therapy. Third, we have performed a clinical study for p53 gene therapy for un-resectable advanced esophageal cancer. This clinical trial was planned to evaluate vector tolerability and efficacy. A total of 10 patients were enrolled into this phase I/II trial.