This study attempts to identify the extent of using authentic materials in the new series of secondary English textbooks ("Flying High for Saudi Arabia") used currently in Saudi schools. Therefore, a content analysis instrument has been designed to analyze the first secondary English textbook. The instrument has been distributed on 112 EFL female teachers who work in public Secondary schools in Riyadh city. The findings show that the selected textbook focuses to a moderate extent on using material authenticity. The provided materials promote genuine communication among EFL learners, prepare learners for the future uses of the target language and present authentic language in its actual contexts. However, the findings reveal that the used materials are beyond the learners' level and the reading comprehension activities present real life texts at a poor range. These findings suggest to adjust the given materials to fulfill the learners' needs and match their proficiency level.