PURPOSE: To describe the MR findings of simple bone cyst. MATERIALS AND METHODS: We analyzed the signal intensity of the cystic contents, their margins, and internal septae, and the presence of bony fragment and pathologic fracture, and enhancement patterns in MRI of 10 pathologically confirmed simple bone cysts. RESULTS: On MR imaging, the cystic contents were of homogeneously low signal intensity on T1WI and high signal intensity on T2WI in nine cases and fluid-fluid level was seen in one case. The cystic margins were dark in all sequences. There were not any fragment in the cysts. Among the four cases with pathologic fracture, one case had fluid-fluid level and two had some areas of enhancement in the cyst or adjacent soft tissue. All nine cases with gadolinium enhancement showed thin rim enhancement along the inner margin of the cysts and internal septae. CONCLUSION: Homogeneous fluid-like signal intensity of cystic content and thin rim enhancement of margin and internal septae in MR imaging are believed to be helpful in the diagnosis of simple bone cyst.