Introduction: Although magnetic resonance imaging (MRI) of ligamentum flavum and other spinal cysts have been well described, the role of contrast enhancement in this diagnosis has been neglected. We describe such a case and correlate the MRI findings with the histopathology. Case report. A 71-years-old woman was admitted with of neurogenic lumbar claudication. X-rays of the lumbar spine showed degenerative changes with scoliosis. Lumbar magnetic resonance imaging demonstrated a L3/4 extradural cystic mass. An L3 laminectomy was performed and the mass excised. The histopathological diagnosis was consistent with a ligamentum flavum cyst. Postoperatively, the patient's symptoms resolved completely. Conclusion: The possibility of a ligamentum flavum cyst should be considered whenever a hyperintense extradural mass with a peripheral hypointense rim on T2 weighted and slightly contrast enhanced peripheral rim on T1 weighted MRI is identified in a patient with degenerative changes of the lumbar spine. (C) 2003 Elsevier Ltd. All rights reserved.