Synovial spinal cysts are typically found in the lumbar spine, most often at the L4-L5 level. Magnetic resonance imaging is the diagnostic imaging of choice in the workup of suspected synovial cysts. This study consisted of 24 patients with lumbar synovial cysts treated by cyst excision and nerve root decompression through partial or complete facetectomy and primary posterolateral fusion. The most common location of the cysts was the L4-L5 segment. Synovial tissue was found in histological sections of 18 cysts. At a mean follow-up of 12 (range, 8 to 24) months, 20 patients (83%) had excellent or good results; two patients (8.3%) had fair and two patients (8.3%) had poor improvement. Operative complications included dural tear in two patients and postoperative wound dehiscence in one patient, which were treated accordingly. To eliminate the risk of recurrence synovial cyst excision through partial or complete facetectomy is required. In addition, since synovial cysts reflect disruption of the facet joint and some degree of instability, primary spinal fusion is recommended.