PURPOSE: In clinically suspected ankylosing spondylitis of sacroiliac (SIJ) and hip joints with normal or minimal secondary bone change in simple X-ray films, we evaluated the role of MRI in sacroiliac and hip joints. MATERIALS AND METHODS: Authors evaluated 11 cases (36 joints;SIJ 14, hip 22) confirmed as spondylitis by clinical, laboratory, and radiologic findings, and compared the detectability of involvement of joints by simple X-ray film and MRI. Authors analysed MR findings for the presence of pannus and its si, intensities (SI), change of articular cartilage, bony erosion and sclerosis, subchondral bone cysts,.~ osteophytosis, bone marrow edema, joint effusion, adjacent soft tissue change, and contrast enhancement ofi pannus. RESULTS: MRI detected not only 20 joints (SIJ 11, hip 9) detected in simple X-ray, but also additional 7 joints (SIJ 3, hip 4). MRI depicted simultaneous involvement of SIJ and hip joints in 5 of 11 cases (SIJ 10 joints, hip9 joints), and bilateral involvement of SIJ and hip joints in 4 among the 5 cases. MRI also demonstrated pannus, which were not detected in conventional films, as intermediate SI on T1WI and high SI on T2WI, in all 27 joints (SIJ 14, Hip 13). Gd-DTPA enhanced T1WI revealed enhancement of pannus in 7 cases (17 joints). CONCLUSION: MRI was a valuable modality in evaluation of clinically suspected ankylosing spondylitis of SIJ or hip joints with normal or minimal secondary bone change in simple X-ray. Simultaneous evaluation of SIJ and hip joints is suggested in clinically suspected ankylosing spondylitis or other joint diseases.