The major purposes of this study were to understand teachers' definitions of e-textbooks, to identify teachers' needs when using e-textbooks and to explore the relationships between teachers' needs of using e-textbooks and teachers' attributes. To achieve these major purposes, an open questionnaire was proposed to experts to obtain their requirements of using e-textbooks. A needs of using e-textbooks perception scale (NUEPS) was then constructed based on teacher interview results, the literature review and the results of the open questionnaire mentioned above. In the formal study, 378 elementary and secondary school teachers were selected to complete NUEPS, and the reliability and validity of the scale were checked. The results indicated that the teachers' needs when using e-textbooks comprised three factors: (1) to support teaching activities (STA); (2) to support reading and presentation (SRP); and (3) to support learning activities and parental interaction (LAPI). Besides, the findings of the study showed that the Taiwanese school teachers' perceptions of using e-textbooks were positive in average. There were no significant differences in terms of gender and age, but there were differences regarding teachers' school level, and application experience in both the STA and SRP sub-dimensions. The results of this study can be used to offer a better understanding of teachers' needs of using e-textbooks, and to help novice teachers' application in e-textbook.