Background: There has been some ground-breaking research on self-directed learning (SDL) in nursing education which reveals the superiority of SDL to traditional learning methods in terms of students' academic performance and the development of positive attitudes toward the learning process on the part of both students and teachers. Objectives: The relationship between students' self-directed learning readiness (SDLR) and students' academic performance, and the mediating role of students' perceptions of the learning environment needs further investigation. In this study, it is proposed that students' perceptions of their learning environment could enhance their SDLR and thus boost their academic performance (in terms of their GPA). Design: A descriptive design was used to examine the relationships between the domains of SDLR, which are self-management, desire to learn and self-control and students' perceptions of the learning environment (SPLE) and students' GPA. Data source: A survey involving 142 Saudi students from nursing and emergency medical services undergraduate programs in King Saud University was used for this research. Results: The results showed that SDLR level positively influenced students' academic performance positively, and that students' perceptions of their learning environment played a significant role in determining their level of SDLR and academic performance. Conclusion: It is recommended that nursing and emergency medical services educators provide a supportive learning environment in terms of good teaching, clear goals and standards, appropriate assessment, appropriate workload, and emphasis on independence to encourage students to engage in the process of SDL which can, in turn, enhance their academic performance. (C) 2015 Elsevier Ltd. All rights reserved.