This study compared the effects of spacing and massed instructions on Iranian English as a foreign language (EFL) learners' reading comprehension. To fulfill this objective, 50 Iranian participants were selected among 80 students based on the results of Oxford Quick Placement Test (OQPT). The intermediate selected participants were then randomly divided into two equal experimental groups; spacing group and massed group. Afterward, the researcher measured the participants' English reading comprehension by administering a reading comprehension pretest. Then, five English texts from Active One Book were instructed to both experimental groups. In the massed class, each text was taught in an intensive 60-min session, whereas each text was taught to the spaced group in three short sessions (about 60 min in total). The first session lasted for 20 min; the second occurring 2 days after the initial session lasted 20 min; and the third session took 20 min and was held 2 days after the second session. After the instruction, a reading posttest was administered to the both groups and finally the data were analyzed by using paired and independent samples t tests. The obtained results indicated that there was a significant difference between the posttests of spacing and massed groups. The findings indicated that the spacing group significantly outperformed the massed group (p < 0.05) on the posttest. The implications of this study can make the teachers aware that teaching through spaced intervals can provide better results than teaching through one massed session.