Background: The Functional Assessment of Chronic Illness Therapy (FACIT) for Dyspnea was developed to assess multidimensional dyspnea using two subscales (experience of dyspnea and functional limitation) and a total score. Objects: This study aimed to assess the reliability and validity of the Korean version of the FACIT-dyspnea 10-item short form questionnaire (FACIT-dyspnea-K). Methods: Subjects were 163 patients with cancer. Dyspnea-related scales (modified Medical Research Council scale [mMRC], European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 [EORTC QLQ-C30], Hospital Anxiety and Depression [HAD], and WHO Performance Scale) were used to validate the FACIT-dyspnea-K. Results: Internal consistency was confirmed by Cronbach’s alpha values of 0.90 and 0.95 in factors 1 and 2, respectively. Convergence validity was determined by comparing the two factors and total score of the FACIT-dyspnea-K with conceptually related assessment tools measuring the physical and emotional effects of dyspnea, with which correlations ranged from 0.364 to 0.567. Criterion validity was established by significant differences in the FACITdyspnea- K score between groups when the patients were classified by performance status as assessed by the WHO performance scale. Furthermore, the FACIT-dyspnea-K showed notable correlations with other dyspnea scales (mMRC, EORTC QLQ-C30, and HAD) for cancer patients (r = 0.28 to 0.54). The test-retest reliability of the two factors and total score of the FACITdyspnea- K appeared to be excellent (Cronbach’s alpha = 0.96 to 0.97). Conclusion: This study supports FACIT-dyspnea-K as a valid and reliable instrument to assess the dyspnea experience of cancer patients in clinical settings.