This study is conducted to analyze the questioning styles of the parts of chemistry in 17 middle school science textbooks in terms of frequency, types, and placement of questions. The instrument was the Textbook Questioning Strategies Assessment Instrument (TQSAI) developed by the Cooperative Teacher Preparation Program, University of California in 1975. An averaged ratio of questionings/sentences (Q/S) of seventeen textbooks was 13.6% varying from 6.8% to 19.7%. Various question types were used in titles, early and middle steps in the sections except late steps. The comprehending questions were most frequent in the types of inquiry courses and the focusing questions were most frequent in the characteristics of instructional courses. The percentages of empirical questions for the total numbers of questions were slightly larger than nonempirical questions with values of 54.2% and 45.8%, respectively.