OBJECTIVE: This study aims at translating and adapting the EQ-5D cross-culturally into Korean (KEQ-5D), and evaluating its reliability and validity among patients with various rheumatic diseases. METHODS: The EQ-5D was translated into Korean by 2 translators and back into English by another 2 translators. Then lay assessment was done according to the EuroQol Group's translation guidelines. Based on the repeated measure data of 65 patients with rheumatoid arthritis (RA), we examined test-retest reliability by intra-class correlation (ICC), and responsiveness by effect size and t-statistic. To evaluate validity, we recruited 100 patients with RA, 103 with osteoarthritis (OA), 111 with systemic lupus erythemtous (SLE), 104 with fibromyalgia syndrome (FMS), and 90 with ankylosing spondylitis (AS). For concurrent validity, we explored correlation between the KEQ-5D and KEQ-VAS(visual analog scale), KSF-36 global, utility measures such as time-trade off (TTO) and standard gamble(SGM), and disease-specific measures, including KHAQ and for RA, KWOMAC for OA, SLEDAI and SLICC for SLE, KFIQ for FMS, and KBASFI for AS. RESULTS: Test-retest reliability measured by ICC was 0.635. The effect size was 0.683. Correlations with KEQ-VAS and SF-36 global were significant, however those with TTO and SGM were not. Correlations with disease-specific measures were all significant except for SLEAI and SLICC in SLE, ranging from -0.477 to -0.603. Correlations between physical domains of KEQ-5D and KSF-36P were higher those with KSF-36M, on the contrary, correlation between anxiety/depression and KSF-36M was higher than that with KSF-36P in both overall and disease-specific analysis. CONCLUSION: These findings indicated that KEQ-5D had stability and responsiveness, and moreover, criterion and construct validity were satisfactory. We concluded that KEQ-5D could be applied to Korean patients with various rheumatic diseases.