Although teacher burnout has drawn the attention of many researchers, there is little empirical evidence for the contribution of non-native English language teachers' language proficiency level to their experience of burnout. To address this significant gap, the present study examined the relationship between English as a foreign language (EFL) teachers' self-assessed language proficiency and their experience of burnout. Research has indicated that personal resources of teachers can function as protectors against their experience of burnout. Thus, it was assumed that investigating how EFL teachers' level of burnout can be reduced through language proficiency as a personal resource can cast a new light on the role of personal resources in reducing teachers' experience of burnout. To this end, data were collected from 110 Iranian EFL teachers who were teaching in private language institutes through the Maslach Burnout Inventory - Educator Survey and Iranian EFL Teacher Self-Reported Language Proficiency Scale. The correlational analysis revealed that language proficiency had a significant negative relationship with the emotional exhaustion and depersonalization dimensions and a significant positive relationship with the personal accomplishment dimension of burnout. The results of regression analysis also indicated that, except for the reading subskill, all the other proficiency subskills were the best predictors of the different dimensions of burnout. Based on the findings of the current study, some pedagogical implications and research suggestions were also proposed.