We investigated the relation between head and neck cancer risk and alcohol consumption in the NIH-AARP Diet and Health Study. During 2 203 500 person-years of follow-up, 611 men and 183 women developed head and neck cancer. With moderate drinking (up to one alcoholic drink per day) as the referent group, non-drinkers showed an increased risk of head and neck cancer (men: hazard ratio (HR) 1.68, 95% confidence interval (95% CI) 1.37 -2.06; women: 1.46, 1.02 -2.08). Among male and female alcohol drinkers, we observed a significant dose -response relationship between alcohol consumption and risk. The HR for consuming 43 drinks per day was significantly higher in women (2.52, 1.46 -4.35) than in men (1.48, 1.15 -1.90; P for interaction ¼ 0.0036). The incidence rates per 100 000 person-years for those who consumed 43 drinks per day were similar in men (77.6) and women (75.3). The higher HRs observed in women resulted from lower incidence rates in the referent group: women (14.7), men (34.4). In summary, drinking 43 alcoholic beverages per day was associated with increased risk in men and women, but consumption of up to one drink per day may be associated with reduced risk relative to non-drinking. British Journal of Cancer (2007) Each year, more than 600 000 individuals are diagnosed with squamous cancers of the head and neck worldwide (Parkin et al, 2005). Head and neck cancer has multiple anatomic sub-sites, including the oral cavity, pharynx, and larynx, which may have distinct aetiologies.Alcohol use has consistently been indicated as a risk factor for head and neck cancer (Sturgis et al, 2004). However, owing to small case numbers, previous prospective studies have typically collapsed cancers of the head and neck and the aesophagus into a single broad category of upper-gastrointestinal tract sites (Gronbaek et al, 1998;Kjaerheim et al, 1998;Boeing, 2002). Few prospective studies have examined the association between alcohol and individual head and neck cancer sub-sites, such as the larynx, oral cavity, or pharynx (Schottenfeld et al, 1974;Boffetta and Garfinkel, 1990;Adami et al, 1992;Tonnesen et al, 1994;Sigvardsson et al, 1996;Boffetta et al, 2001). Most of these studies have not adjusted for tobacco use, an important potential confounder of the relation between alcohol and head and neck cancer (Boffetta and Garfinkel, 1990). Also, few studies (Franceschi et al, 1994;Gronbaek et al, 1998;Hayes et al, 1999;Castellsague et al, 2004;Polesel et al, 2005) have examined non-drinkers and those that drink less than two drinks per day separately, an important comparison as consumption of less than two drinks per day may reduce cardiovascular disease risk (Maclure, 1993).Although men are 2 -7 times more likely to develop these cancers than women (depending on sub-site) (Parkin et al, 2005), few epidemiological studies have compared the association of alcohol and head and neck cancer in men to that in women (Blot et al, 1988;Franceschi et al, 1994;Hayes et al, 1999;Boffetta et al, 2001). These studies generally indicate...