Abstract Background context Acute onset of radicular symptoms has been reported following hemorrhage into lumbar synovial cysts after trauma or in cases of spinal instability. No previous cases have been linked to anticoagulation therapy. Purpose To present a case of symptomatic hemorrhagic lumbar synovial cyst occurring after anticoagulation therapy. Study design A case report and review of the literature. Methods A patient presented with low back and radicular pain secondary to a large synovial facet cyst. Magnetic resonance imaging revealed a large facet cyst compressing the thecal sac and L3 exiting nerve root. Results The synovial cyst was excised during a lumbar decompression and fusion. Gross blood was present in the cyst. Conclusions This is the first reported case of symptomatic hemorrhagic lumbar facet cyst associated with anticoagulation therapy.