The purpose of this project report is to make a small corpus of relative clauses found in some Japanese junior/senior high EFL textbooks and Malaysian senior high ESL textbooks, and to examine the distribution and features of the use of relative clauses in them. English relative clauses follow the head noun, which is true in most European languages; in contrast, Japanese, Chinese, and Korean all require that the relative clauses occur before the head noun, so native speakers of these Asian languages will have some difficulty in grasping this fundamental syntactic difference in learning English. Considering that a textbook is the single most important resource of input for learners, it will be of vital importance to know what kinds of usage samples are available for learners through textbooks. In this study, sentences using relative clauses were collected from the analyzed textbooks and over 1,000 samples were collected and categorized based on the categories provided by Ellis (1994). As a result, this study identified similarity in terms of the frequency and features of relative clauses used in both countries’ English textbooks and also gave evidence of influence on Japanese students’ writings in English.