The effects of sodium chloride and alcohol on esophageal carcinogenesis induced by N-nitrosopiperidine (NNP) were studied in male F-344 rats. Sodium chloride given concomitantly with NNP during the first 8 weeks of the experiment and followed by sodium chloride increased the incidence of esophageal tumors in week 20. Sodium chloride given after NNP during the second 12 weeks of the experiment increased the incidence of esophageal hyperplasia. In the present experiment, no clear effect of alcohol on esophageal carcinogenesis was demonstrated, but alcohol slightly increased the incidence of preneoplastic esophageal tumors in groups given alcohol with and after NNP. These results suggest that sodium chloride may be able to be a potent promoter of the development of esophageal tumors in rats if the conditions of initiation are appropriate. Examination of the incidences of tumors in 9 segments of the esophagus gave no evidence of any portion that was especially susceptible to induction of esophageal tumors.