The ethnographic study was conducted in two communities in Oyo State in Southwestern Nigeria. The study sites consisted of a rural and an urban local government area located in the tropical rain forest zone of Nigeria. The study was designed to obtain information on febrile illnesses and herbal remedies for treatment with the aim of identifying potential antimalarial drugs. The study revealed that fever is a general term for describing illnesses associated with elevated body temperature. The indigenous Yoruba ethnic population has categorized fever based on symptoms and causes. The present communication is the result of focus group discussion and semi-structured questionnaire administered to traditional healers, herb sellers, elders and mothers. This was on types of fevers, symptoms and causes of febrile illnesses. The investigation also included use of traditional herbs in the prevention and treatment of the illnesses in the two communities.