Large class size is one of the problems in the educational sector that developing nations have been grappling with. Nigeria as a developing nation is no exception. The purpose of this study is to provide views of both lecturers and students on large class size and how it affects teaching and learning in tertiary institutions in Ekiti State of Nigeria. The study employed survey design; the population consisted of all lecturers and students in College of Education in Ikere-Ekiti, Ekiti State, University of Nigeria, Nsukka, Ikere Campus and Ekiti State University, Ado Ekiti, Ekiti State. The total populations of thirty (30) lecturers were used for the sample, while five hundred and twenty (520) final year students were randomly selected. The research instruments used in data collection were questionnaire. The findings of this study revealed that large class size has negative implications on effective teaching and learning of Business Education in tertiary institutions. The relationship between large class and effective teaching and learning is very low. The authors recommended among others that management should employ more lecturers for the teaching of Business Education in tertiary institutions if they want to admit large number of students because of income, also the institution should make extra effort to provide more resources and facilities to promote effective teaching and learning of Business Education.