The connections and possible interactions between coffee consumption, tobacco consumption, blood pressure (BP), age, and body mass index (BMI) were analysed in a cross-sectional epidemiologic study of 1098 men and 393 women of the Algiers district. Systolic blood pressure (SBP) was negatively and significatively correlated with cigarette smoking. Diastolic blood pressure (DBP) was positively and significantly associated with coffee consumption (P less than 0.001) and negatively and significantly with cigarette consumption (P less than 0.001). These associations remained significant after multivariate analysis including sex, age, BMI, physical exertion at work, athletic activity, rural versus urban residency, tobacco, tea and coffee consumption. Coffee consumption and cigarette smoking were positively associated (P less than 0.001). In the subgroup of men, the association between coffee consumption and DBP was significant only after adjustment for cigarette smoking. In the subgroup of women, containing a low percentage of smokers, this association was significant without such adjustment. This finding suggests that cigarette consumption might partly mask the association between coffee consumption and BP. The contradictory interactions observed between BP, cigarette consumption and coffee consumption might help to explain the conflicting reports concerning the association between coffee consumption and ischemic heart disease.