A strong, dose-dependent association exists between alcohol consumption and risk of cancer of the oral cavity and pharynx. The impact on risk of temporal aspects of drinking habits has been inadequately evaluated. Our case-control study included 754 individuals with incident cancer of the oral cavity and pharynx (median age 57) and 1,775 controls (median age 57) in the hospital for acute, non-neoplastic diseases who were interviewed in 2 Italian areas and in the Swiss Canton of Vaud between 1992 and 1997. The questionnaire included lifetime drinking and smoking habits. No influence of age at starting or duration of alcohol drinking was found. Risk increased substantially with the increase of weekly alcoholic drinks [Odds Ratios (OR) for >/= 91 drinks/week vs. never drinkers = 11.6]. Risk in former compared with current drinkers was 1.9-fold elevated. However, among individuals who had also stopped smoking, former drinkers showed lower ORs than current drinkers. The persistence of risk elevation several years after drinking cessation suggests that the role of alcohol is complex and it probably affects more than one stage of oral carcinogenesis. It remains to be clarified which impact prevention-driven drinking cessation may have on the excess of cancer of the oral cavity and pharynx due to elevated alcohol intake.