Incidence rates by income level were computed for squamous cell carcinomas of the gum and mouth, larynx, and esophagus and for squamous cell carcinoma, small cell carcinoma, and adenocarcinoma of the lung in white males and females aged 35--64 years, with the use of data for the nine geographic areas of the Third National Cancer Survey and the 1970 U.S. census. Within sex, age, and geographic area groups, patterns of cancer incidence by income level were analyzed by use of a nonparametric statistical method. Higher rates for males than for females were found for every histologic type studied, and the ratio of male-to-female rates increased with age (especially for squamous cell carcinomas of the larynx and lung). A strong inverse relation to income level was found for all of the histologic types studied in males and for squamous cell carcinomas of the gum and mouth and esophagus and small cell carcinoma of the lung in females. These findings are discussed with reference to patterns of smoking and alcohol use by sex and social class.