An Ethnobotanical survey of medicinal plants used in Ona Ara, Ido, Egbeda and Lagelu Local Government Areas of Oyo State, Nigeria through administration of structured questionnaires and oral interview. The respondents include herb sellers, farmers, traditional medicine practitioners, and indigenes/residents. Respondents were able to provide local names of the plant species and their medicinal uses. The prevalent disease conditions traditional healers uses these plants for includes: anti-malaria, cold, anti-fungal, Arthritis , skin problems, fever, blood pressure control, measles, cough, headache, diarrhea, anti-bacteria, fertility problems, toothache, common cold, measles etc. The result shows that majority of the respondents (71.15 %) were males and married (73.46%) while most (66.92%) were above 40 years of age. A total of 67 species of medicinal plants belonging to 37 families obtained from 260 respondents were identified and documented. Among these plants, 54% tree, 16% shrub and 30% herbs were recorded. The most dominant families in the study were Fabaceae (11.9%), Asteraceae (7.5%), Malvaceae (5.9%), Anarcardiceae, Rubiaceae, Poaceae, Zingiberaceae, Euphorbiaceae (4.5% each), Bombacaceae, Arecaceae, Annonaceae, Apocynaceae, Moraceae, Leguminosae (2.9%each).The other plant families have one member each in the distribution of species within the families. The survey also observed that the following plant parts were used; leaves, stems, flowers, bulbs, barks, roots, fruit, oil, seeds/nuts, juice/sap, rhizome and whole plant. Percentage representation of the plant parts used revealed that leaf was most frequently used. The methods of preparation mostly preferred are decoction and infusion, others include maceration, cooking as meal/soup, crushing/grinding, and burning/roasting. The R2 value of 0.015 indicates that a very small percentage of the variables does not have effect on the choice of plants parts used for medicine. It is therefore concluded that most persons in the rural area prefer the use of medicinal plants in the treatment of diseases for the reason of affordability, availability, effectiveness and accessibility of practitioners. It is recommended that Government should create awareness and organize programmes against deforestation. Awareness regarding the conservation status of rare medicinal plants, domestication strategies as well as appropriate methods of exploitation is very important for further studies to ensure availability of these plants and a sustainable utilization.