A simple bone cyst located in the spine is rare. In the current work, we have documented the first case of a simple bone cyst located in the pedicle of the lumbar vertebra. The patient was a 50-year-old woman with low back pain. Radiographs of the lumbar region of the spine showed a well circumscribed radiolucent lesion with surrounding bone sclerosis in the right pedicle of L3. Computed tomography (CT) showed that the right pedicle was completely occupied by the cyst and slightly expanded. The cystic lesion extended to both the vertebral body and the lamina. T1-weighted magnetic resonance imaging (MRI) showed uniform low intensity, and T2-weighted MRI showed uniform very high intensity. Signal enhancement by gadolinium diethylenetriaminepenta-acetic acid was not observed in the lesion. During the operation, the cavity of the cyst was filled with 2 mL of serosanguinous fluid. Subsequent histologic examination showed a thin layer of connective tissue in the inner surface of the cyst.