Data from nine US population-based cancer registries participating in the Surveillance, Epidemiology, and End Results (SEER) program from 1973 through 1982 were analyzed to examine demographic characteristics related to the occurrence of the two major types of cancer of the esophagus. The overall annual incidence rate per 100,000 persons was 2.6 for squamous cell carcinoma and 0.4 for adenocarcinoma. The sex ratio for adenocarcinoma varied from one age group to the next and was highest in the 50- to 59-year-old group. It was relatively the same for squamous cell carcinoma. The male-to-female ratio was higher for adenocarcinoma (seven in whites and 10 in blacks) than for squamous cell carcinoma (three and four, respectively). The highest sex-specific ratio for adenocarcinoma occurred in the lower third of the esophagus. Blacks had a fourfold to fivefold higher rate of squamous cell carcinoma than whites, but the rate of adenocarcinoma in blacks was 30% of the rate in whites. The incidence of squamous cell carcinoma in black men and women increased by approximately 30% between 1973 and 1982, and the rate of adenocarcinoma among white men increased 74%. Nearly half of the squamous cell carcinomas occurred in the middle of the esophagus, whereas the majority (79%) of the adenocarcinomas arose in the lower third. These data suggest that the two major histologic types of esophageal cancer may be of different etiologic origin.