This survey studies the opinion of the French general population, general practitioners and pediatricians regarding mandatory immunization. Data were collected through standardized telephone questionnaires administered to representative samples of the French population (n = 4112) and of French general practitioners and pediatricians (1285 general practitioners (GPs) and 742 pediatricians). 56.5% of the general population is in favor of mandatory vaccination. Being in favor of hepatitis B vaccination, agreeing that "it would be important to continue immunizing against diphtheria in case immunization was made optional" or saying that "if immunization against diphtheria was discontinued, the disease would spread again", are some of the main determinants of a favorable opinion regarding mandatory immunization. The percentage of GPs and pediatricians in favor of mandatory immunization is 42%. Female pediatricians and those who would "insist on families in the importance of continuing immunizing all children against diphtheria in case this vaccination was only recommended" more often declare themselves in favor of mandatory immunization. The adoption of the principle of mandatory immunization seems to stem from the adoption of immunization as an individual and collective prevention tool.[résumé auteur]