The present study is concerned with the relationship between brain hemisphericity and the reading comprehension of adult Saudi EFL learners. The tendency to rely on one side of the brain over the other can affect the degree of success in learning a foreign language as well as the appropriateness of learning and teaching strategies. A total of 122 Saudi university-level participated in the study. The first part of the study examines whether or not there are significant differences between the performance of right-brained learners, left-brained learners, whole-brained learners, whole-brained learners favoring right mode, and whole-brained learners favoring left mode in an EFL reading comprehension test. The EFL reading comprehension includes main idea questions, inferential questions, literal-meaning questions and text-bound questions. The Hemispheric Mode Indicator® is used to determine hemispheric preference of the participants. Findings revealed significant superiority of the performance of left-brained learners as compared to right-brained learners and whole-brained learners favoring right mode. This result suggests that even in a foreign language learned after childhood, the left-hemisphere seems to control brain activities dealing with language. In the second part of the study, participants were trained to use a visual tool (Mind Mapping ®) to summarize the information of the reading passage before answering a parallel reading comprehension test. Whole-brained learners favoring right mode, and right-brained learners were the two groups who benefited the most from the visual tool. This result was expected since the visual tool activates some right hemispheric functions. It is concluded that learners with different modes of hemisphericity learn in different ways.