A series of three doses of recombinant canary-pox-vectored canine distemper virus vaccine was administered at 1-mo intervals, orally (n = 8) or intramuscularly (n = 13), to 21 previously unvaccinated juvenile African wild dogs (Lycaon pictus) at the Wildlife Conservation Society's Bronx Zoo. Titers were measured by serum neutralization at each vaccination and at intervals over a period of 3.5-21.5 mo after the initial vaccination. All postvaccination titers were negative for orally vaccinated animals at all sampling time points. Of the animals that received intramuscular vaccinations, 100% had presumed protective titers by the end of the course of vaccination, but only 50% of those sampled at 6.5 mo postvaccination had positive titers. None of the three animals sampled at 21.5 mo postvaccination had positive titers.