Using corpus approach, over the past two decades, a growing number of researchers started to blame textbooks for neglecting important information on the use of grammatical structures in real language use and provided ample information about the mismatch between language used in textbooks and real language in use. Likewise, the prescribed Malaysian English textbooks used in schools are reportedly prepared through a process of material development that involves intuition and assumption. Hence, a corpus-based study was adopted here to allow the researchers to identify modal auxiliary verbs' order and ranking in both whole text-types and spoken text-type of five Malaysian English language textbooks. This study has revealed that for almost all of the modal auxiliaries, there is a discrepancy between frequency order in the textbook corpus and the three major reference corpora. The findings of this study also show that the currently used pedagogical language in Malaysian textbooks is mainly based on written rather than spoken English. This study does not suggest making drastic changes in the Malaysian textbooks in order to create a textbook that mirrors exactly the language used by native speakers. However, the most salient facts reflected from natural language corpora should not be ignored in the textbooks.