Docetaxel (DOC) has demonstrated an activity as a radiation sensitizer in head and neck cancer. We have experienced four cases of esophageal cancer treated by weekly DOC in combination with concomitant radiotherapy. Three cases of advanced esophageal cancer and a case of relapsed esophageal cancer after administration of 5-FU and CDDP were enrolled in this pilot trial. The schedule of treatment included a weekly administration of DOC (10 mg/m2/w) and six weeks of radiotherapy in 2.0 Gy daily fractions up to 60 Gy. Combination treatments were completed successfully without any side effects except a case of developed grade 1 dysphagia. Two cases showed a complete response and others showed a partial response. One case showed a complete response developed abdominal para aortic lymph node and liver recurrence 12 months after the treatment. However, the targeted lesion within radiotherapy for this patient still showed a complete response. A weekly administration of low dose DOC in combination with radiotherapy was very effective for advanced esophageal cancer. DOC has demonstrated an activity as a radiation sensitizer.