BACKGROUND: Several studies have explored physicians' attitudes towards prevention and barriers to the delivery of preventive health interventions. However, the relative importance of these previously identified barriers, both in general terms and in the context of a number of specific preventive interventions, has not been identified. Certain barriers may only pertain to a subset of preventive interventions. OBJECTIVES: We aimed to determine the relative importance of identified barriers to preventive interventions and to explore the association between physicians' characteristics and their attitudes towards prevention. METHODS: We conducted a cross-sectional survey of 496 of the 686 (72.3% response rate) generalist physicians from three Swiss cantons through a questionnaire asking physicians to rate the general importance of eight preventive health strategies and the relative importance of seven commonly cited barriers in relation to each specific preventive health strategy. RESULTS: The proportion of physicians rating each preventive intervention as being important varied from 76% for colorectal cancer screening to 100% for blood pressure control. Lack of time and lack of patient interest were generally considered to be important barriers by 41% and 44% of physicians, respectively, but the importance of these two barriers tended to be specifically higher for counselling-based interventions. Lack of training was most notably a barrier to counselling about alcohol and nutrition. Four characteristics of physicians predicted negative attitudes toward alcohol and smoking counselling: consumption of more than three alcoholic drinks per day [odds ratio (OR) = 8.4], sedentary lifestyle (OR = 3.4), lack of national certification (OR = 2.2) and lack of awareness of their own blood pressure (OR = 2.0). CONCLUSIONS: The relative importance of specific barriers varies across preventive interventions. This points to a need for tailored practice interventions targeting the specific barriers that impede a given preventive service. The negative influence of physicians' own health behaviours indicates a need for associated population-based interventions that reduce the prevalence of high-risk behaviours in the population as a whole.