The present study attempted to investigate the effect of multimedia glosses on EFL students' vocabulary acquisition and retention. Forty-five EFL students were divided into two groups: control (n=22) and experimental (n=23). A vocabulary test was administered to both groups in order to ensure that they were equivalent. Then, all participants attended 12 weekly reading sessions where participants of the experimental group practiced reading computerized texts that included multimedia glosses while participants of the control group practiced reading the same texts but without any glosses. Immediately after the treatment was over, the vocabulary test was administered to both groups in order to evaluate the differences between the two groups in vocabulary acquisition. Moreover, the same test was administered to both groups two weeks after the administration of the posttest with the purpose of evaluating the differences between the two groups in vocabulary retention. The statistical analysis revealed a significant difference between the two groups in both the immediate and the delayed administrations of the vocabulary test. Therefore, it was concluded that multimedia glosses enhanced both vocabulary acquisition and retention among EFL students.