The purpose of this study   is to investigate the effect of using Arabic in English classes. To achieve this purpose, the researchers distributed   a questionnaire about the use of Arabic in English classes to the teachers and students of ordinary-level English at Rawdat Al-Ma’aref Schools and College (R.A.M.S) in Amman, Jordan.  The results of the study showed that 100% of the students and 90% of the teachers felt that Arabic should be used in their English classes. The respondents emphasized the fact that cultural and religious concepts should be taught by referring to Arabic in English classes. A noticeable percentage of 90% of students agreed that Arabic should necessarily be used to explain difficult concepts. Almost a similar percentage of   the students like to have Arabic in their grammar lessons because they feel that it facilitates their learning of English. The findings of the study should be taken into consideration by teachers of English as a foreign language as well as textbooks and curricula designers.