This research aims at examining the reactions of tertiary EFL teachers towards the use of performance-based language assessment. The study employed a mixed-method research methodology. For the quantitative method, 36 teachers responded to a questionnaire survey. In addition, four teachers participated in the in-depth interviews which were conducted twice, at the beginning and at the end of the semester. The data from the survey revealed that the teachers were aware that the assessments (performance-based and traditional methods) could have both positive and negative impacts on teaching and learning. In addition, the participants in the interviews pointed out that they had rather negative attitudes toward the performance-based assessment used, after it had been implemented for over six years, because there were weaknesses in the assessment especially concerning tasks, rating scales, and rater training. They recommended that the rating scales should be revised and the rater training should be vigorously implemented to ensure the quality of the assessment process.