Tobacco smoke (TS) is the single most important cause of preventable death in industrialized countries. Health staff have great responsibility in its control, but the smoking habits of health staff may influence their attitude toward patients. The aim of the study was to evaluate: 1) the prevalence of smoking among health staff at different professional levels; 2) the knowledge of smoking-related damage; and 3) how personal smoking habits influence behaviour in the workplace. A questionnaire was sent to all health staff of the Morelli Hospital (Sondalo, Italy) asking information about age, activity, smoking habits and attitude toward smoking: the Fagerstrom test was also administered to smokers. A total of 959 valid questionnaires were collected (57% of the whole sample). Results were analyzed by means of Chi-squared and Student t-tests, where appropriate. The prevalence of smokers was 44% former smokers 24% and lifetime nonsmokers 32%. The highest prevalence of TS was found in nursing students and auxiliaries (47%) and the lowest among doctors (39%). A clear cohort-effect due to age was evidenced: the youngest age-group (< 30 yrs old) presents the highest prevalence of lifetime nonsmokers and of light smokers, and the lowest of heavy smokers; the oldest age-group (> 40 yrs old) presents the highest prevalence of quitters and of heavy smokers, and the lowest of smokers and lifetime nonsmokers; the intermediate age-group (31-40 yrs old) presents the highest prevalence of smokers. The knowledge of smoking-related damage was poor, with significant differences between smokers and nonsmokers and the different professional categories. Tobacco smoking proved to be common behaviour (even when on duty) among health staff. A minority of health staff seem fully aware of personal and social smoking related aspects. Smoking habits influence the attitude of health staff toward patient counselling about tobacco smoking.