Willingness to communicate can be considered as one of the important factors in modern language pedagogy which put emphasis on meaningful communication. The present study investigated the effect of class size on the Iranian EFL students' willingness to communicate among three different class sizes. The researcher collected the data through observation of three classes in terms of students' turn of talk and talk time. Descriptive statistics including mean and standard deviation and one way ANOVA were run to analyze the data. The results of the study indicated that class size had a substantial effect on the students' willingness to communicate. Students were found to be more willing to communicate in small classes where they had more opportunity to practice oral skills and communicate. The current study had some pedagogical implications for both second language teaching and learning at the end.