The purposes of this study were to study the effects of using task-based learning (TBL) to teach English for Academic Purposes (EAP) students and to explore their opinions towards TBL at Thammasat University. Forty students were chosen via purposely selected sampling. The research instruments included a reading and writing pretest-posttest, a speaking pretest-posttest, and a questionnaire. The questionnaire was divided into three parts: the students’ demographic information, the students’ opinions about Pre-Task, During Task or Task Cycle, and Post-Task, as well as their additional opinions and suggestions of TBL. The data was statistically analyzed by mean, standard deviation, and t-test for dependent samples. The results of this study indicated that the reading-writing and speaking abilities of EAP students through TBL after the experiment were significantly higher at the .05 level. Similarly, they were highly satisfied to study with TBL.