Among the 301 dogs vaccinated against rabies in a suburban area of Tunis, 165 were sero-surveyed for 13 months. One month after vaccination, 65% of the dogs less than 1 year of age and 76-84% of the older dogs had significant antibody titers. One month after annual revaccination, these percentages ranged between 92% and 100%. Puppies (less than 3 months old) responded to vaccination with no significant interference by passive maternal immunity. Based on these percentages, a 93% rate of protection may be expected for vaccinated dogs. This study confirms that all dogs (even those less than 3 months of age) must be vaccinated during mass campaigns. The expected protection conferred by locally produced potent vaccines reaches 79-99% based on the age of the dogs. The alleged relative inability of local dogs to respond to vaccination cannot explain the partial success of rabies control in Tunisia.