The purposes of this study were 1) to investigate students’ vocabulary acquisition and retention after learning the English vocabulary online lessons; 2) to explore the students’ satisfaction toward the English vocabulary online lessons and 3) to study the relationship between students’ satisfaction towards the English vocabulary online lessons and the students’ vocabulary acquisition and retention. The samples of this study were 30 third-year students studying in the academic year 2012 at Rajamangala University of Technology Srivijaya (RMYTSV), Trang Campus. English vocabulary online lessons, a vocabulary achievement test and questionnaires on learners’ satisfaction toward the lessons were used as the instruments for collecting data. The statistics for analy ing data were mean ), standard deviation (S.D.), t-test and Pearson’s Correlation Coefficient. The results revealed that after learning the English vocabulary online lessons students’ knowledge of the learned vocabulary increased at a significant level .01. The students’ satisfaction toward learning vocabulary through the English vocabulary online lessons was at high level .31) tudents reported that they could learn better from the exercises of the English vocabulary online lessons at the highest level = 4.57) because they could check the answers and scores immediately after doing the exercises. The students’ satisfaction; however, was not found statistically related to their vocabulary achievement.