This study investigates the effects of extensive reading of e-books on tertiary level EFL students' English reading attitude, reading comprehension and vocabulary. Eighty-nine participants were assigned in two groups, with 46 students in the experimental group and the other 43 students in the control group. In addition to a traditional curriculum for both groups, a ten-week e-book extensive reading program was conducted for the experimental group by encouraging students to read the materials freely from three e-book library collections categorized on the basis of level of difficulty. In contrast, the control group did not engage in any extensive reading program. Stokmans's Reading Attitude questionnaire and TOEFL reading comprehension and vocabulary test were employed to collect the data. The findings of the study showed that the experimental group exhibited significantly better reading attitude, reading comprehension and vocabulary than the control group. Therefore, integrating e-books extensive reading program into EFL teaching program helps improve tertiary level EFL students' reading attitude, reading comprehension and vocabulary learning. (Contains 2 tables.)