The incidence data from nine population-based cancer registries participating in the Surveillance, Epidemiology and End Results program in the U.S. suggest that squamous cell carcinoma arising from different parts of the larynx have different etiologic influences. The male to female rate ratio for laryngeal cancers was substantially higher in the glottic region (9.2 among whites and 11.8 among blacks) than in other subsites (approx. 3-5 in both races). The sex rate ratios were uniformly higher for glottic tumors in all age groups, and these ratios increased more rapidly with age for glottic than for supraglottic tumors. Factors that are closely related to sex other than smoking and drinking behavior are responsible for the considerably high ratio of male to female rates of the glottic tumors. Future etiologic studies should investigate the possible differential effect of hormonal or other sex-related factors on different anatomic subsites within the larynx.