This paper reports on a quasi-experimental study on the effect of vocabulary practice using the Moodle Quiz module on students’ vocabulary learning. Two intact classes including 73 tenth graders were randomly assigned as the experimental group and the control group. Both groups received formal face-to-face English instruction based on an English textbook for tenth Graders. The difference is that the control group did the usual paper-based vocabulary quizzes, whereas the experimental group worked on the same quizzes which were manipulated by Moodle Quiz. Vocabulary achievement tests were administered to measure the vocabulary retention of the participants before the intervention, at the end, and after a delayed period. The results showed that the experimental group had better vocabulary retention than the control group. Cohen’s effect size test further indicated that the effect on vocabulary retention was of a large degree. Further exploration showed that the participants were engaged and motivated to practice vocabulary on Moodle. Findings of the study and confirm the effectiveness of blended learning in EFL instruction, and lend support to the use of technology to compensate limited classroom instruction, and create enhanced practice opportunities for EFL learners.