Tensaw virus inoculated into various vertebrates by the subcutaneous route produced no outward signs of infection. Viremias of highest levels and of greatest duration occurred in dogs, rabbits, and cotton rats. Chickens and English sparrows were resistant. Transmission of Tensaw virus from infected dogs to suckling mice was accomplished in the laboratory by Anopheles quadrimaculatus Say; transmission rates up to 100% were obtained. Results obtained from intrathoracic inoculation of Tensaw virus into Culex quinquefasciatus Say indicated this species to be an unlikely vector.