Laryngeal cancer is the neoplasm with the largest male to female sex ratio in most populations. Thus, inadequate data are available on women. We analyzed several risk factors in the combined dataset from two case-control studies conducted between 1986 and 2000 in northern Italy and Switzerland. Cases were 68 women under age 79 years, with incident, histologically confirmed cancer of the larynx. Controls were 340 women, admitted to the same network of hospitals as cases, for acute, nonmalignant conditions, unrelated to tobacco and alcohol consumption. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated by logistic regression models, conditioned by age, study center and year of interview, and including terms for education, body mass index, tobacco, alcohol drinking, and nonalcohol energy intake. Laryngeal cancer was strongly associated with cigarette smoking (OR = 435.7, 95% CI: 38.2-4964.4 for smokers of >/=25 cigarettes/day) and alcohol drinking (OR = 4.3, 95% CI: 0.8-24.1 for >/=5 drinks/day). An inverse relation was found for vegetables (OR = 0.3, 95% CI: 0.1-0.9 for the highest level of consumption), fruit (OR = 0.5, 95% CI: 0.2-1.3), and olive oil (OR = 0.3, 95% CI: 0.1-0.9). Reproductive and hormonal factors were not consistently associated to laryngeal cancer risk. This investigation, based on a uniquely large number of laryngeal cancers in women, provides definite evidence that cigarette smoking is the prominent risk factor for laryngeal cancer in women, accounting for 78% of cases in this population. Alcohol and selected dietary aspects account for approximately 30% of cases, whereas menstrual and hormonal factors do not appear to have a consistent role in laryngeal carcinogenesis.