We report the case of a hemorrhagic lumbar juxta facet cyst (L2-L3), revealed by a chronic right lumbocruralgia, in a 77-year-old woman treated by anticoagulants for cardiac arrhythmia. Computerized tomography and magnetic resonance imaging suggested the diagnosis of benign tumor. During surgical removal of the whole lesion, a hemorrhagic synovial cyst was evoked. The operation dramatically relieved the symptoms. The diagnosis was confirmed by the histopathological analysis confronted with the clinical and the radiological findings. This uncommon observation allows the discussion of the pathogenic mechanism and of the differential diagnosis.