Objectives: The purpose of this study was to investigate the effects of vocabulary intervention based on morphological awareness on the vocabulary ability of elementary school students with reading disabilities. Methods: A multiple baseline probe design across participants was used to verify the effects of the intervention. The subjects were three elementary school students with reading disabilities (two 3rd graders and one 4th grader). Vocabulary tests at the word level and sentence/paragraph level were conducted at the baseline, intervention, and maintenance phases. The vocabulary intervention based on morphological awareness consisted of 18 sessions (40-50 minutes for a session, 3 sessions per week) and five stages each session. Results: All subjects improved their vocabulary ability in both the word level and the sentence/paragraph level. Furthermore, the vocabulary scores of the subjects during the maintenance phase were close to the scores of the intervention phase. Conclusion: This study shows that vocabulary intervention based on morphological awareness is effective for improving the vocabulary ability of elementary school students with reading disabilities. Understanding the morphological structure of vocabulary helps learners with reading disabilities to improve some quantitative and qualitative growth of vocabulary and also has positive effects on the ability to read and understand texts.