Background and Objective: Despite the number of literature on ethnopharmacological studies in Nigeria, there seems to be no published works on the antiulcer plants used among the people of Ogun and Kwara States of Nigeria. This study was aimed at presenting results of ethnopharmacological survey of the plants used in the treatment of gastric ulcer in Ado-Odo/Ota local government area, Ogun State, Southwestern Nigeria and Ilorin-West and Irepodun local government areas, Kwara State, North central Nigeria. Materials and Methods: Sixty-three respondents, including the old, those who grows and sell herbs and the herb hawkers were interacted with using semi-structured questionnaires. The interviewees were 40 males and 23 females and their ages ranged from 28-70 years. The use-mentions index was calculated for each plant. Results: In total, 62 plant species from 40 families were identified. Famous among these plant families were Compositae, Euphorbiaceae and Leguminosae having 5 and 4 species, respectively. The most used plant species for the treatment of peptic ulcer were: Carica papaya L. (40%) (Caricaceae), Zingiber officinale Roscoe (27%) (Zingiberaceae), Musa paradisiaca L. (40%) (Musaceae) and Allium sativum L. (20%) (Amaryllidaceae). Infusion, decoction and concoction were ways of preparing these mixtures, which were to be taken orally, at least 3 times every day for a specified period. Conclusion: Herbalists have used the plants in this survey several times to treat their peptic ulcer patients and according to them were very effective.