Canine distemper is an acute to subacute contagious febrile and often fatal disease with respiratory gastrointestinal and CNS manifestations which caused by canine distemper virus (CDV), a morbillivirus in the paramixoviridae family. The purpose of this study was to evaluate the prevalence of antibodies to CDV in unvaccinated rural dogs without known immunization status and to assess risk factors for infection by means of indirect immunofluorescent test (IFA), in Ahvaz district, southwest of Iran. Serum samples were randomly collected from 97 healthy dogs greater than six months old from six villages around Ahvaz city between 2004 and 2005. We considered titers > or = 1:10 indicative of an adequate antibody response. Dogs were grouped by age, sex, and area to determine whether these factors were associated with antibody titers, using fisher's exact test. Seroprevalence to CDV antibodies in these dogs were 17.52% indicating that this virus is present in the ecosystem. Also there is evidence of previous natural exposure to CDV. Prevalence of antibodies to CDV did not differ among various regions or between sexes or ages (P>0.05). Rural dogs are abundant in the ecosystem of area and interact with other species of wild carnivores and domestic animals in ways that could encourage disease transmission. The prevalence of CDV antibody-positive dogs do not indicates protection against canine distemper, thus these dogs also may be affected. Therefore we should direct future guidelines for translocations, including quarantine of seropositive dogs and preventing contact between them and domestic pets. Also the role of rural dogs in the epizootiology of CDV in both urban dogs and wildlife needs to be further explored.