Subrenal Capsule Assay (SRCA) as a chemosensitivity test was performed on 14 esophageal squamous cell carcinomas in order to select a more effective form of chemotherapy. Of the 14 assays, 12 were evaluable. Mice were treated with anticancer agents (e.g. Cisplatin, Bleomycin, Methotrexate, Vindesine) on days 1 and 3 after transplantation, and on day 6, the sensitivities were determined. Fresh esophageal cancers yielded an evaluable assay rate of 74%. The implant grew progressively for six days in the remaining group of control mice. Histologically, host cell infiltration at the border of the implant was observed from day 3 after transplantation, and cells had degenerated or had been partially replaced by scar tissue by day 6. The results of chemosensitivity tests differed according to the anticancer agent used or from case to case. Clinically, correspondence between the assay results and clinical results was obtained in 5 out of 7 cases. SRCA is a new promising chemosensitivity test which is clinically useful, and the present results indicated the feasibility of its use in developing an effective chemotherapy for esophageal cancer.