This study investigated the relationship between motivation and language proficiency of Iranian EFL learners studying in Universiti Teknologi Malaysia [UTM]. Two aspects of motivation were considered in this paper i.e. instrumental and integrative. 100 Iranian students studying in UTM and from different faculties served as respondents to reflect a variety of ideas about learning a second language. Participants were those with IELTS band score 6 and above [high achievers] and below 6 [low achievers]. An integrative and instrumental motivation nineteen-item questionnaire adopted from standardized questionnaires such as Attitude Motivation Test Battery (AMTB) [1 & 2] was used as the instrument of the study. The results of correlation study revealed that high achievers’ language proficiency correlated well with integrative motivation [r=.72]. This indicated that high achievers L2 learners were highly integrative motivated.