A preliminary use of Peplomycin (PEP) was investigated in 14 patients with advanced esophageal cancer. PEP was given intermittently with a dose of 10 mg intravenously twice a week. As side effects there were observed fever elevation in 8 cases, stomatitis in 4 cases, erosion of the skin of the scrotum in 1 case and pigmentation in 1 case, respectively. Dyspnea associated with decrease of PaO2 was observed in 4 cases, which recovered promptly after discontinuing of the administration. Out of 10 evaluable cases, partial response was observed in 1, minor response in 1, no change in 3 and progressive disease in 5 cases, respectively. While the effect was only limited in these experiences, the local injection of PEP into or around the tumor using the external fistula of the remaining esophagus which was made at the time of by-pass operation was discussed.