A 75-year-old male presented with groin pain after an operation to treat lumbar spondylolisthesis (L5). Groin tenderness was localized to the medial border of the anterior superior iliac spine (ASIS). Radiographical and physical examination raised the suspicion of sacroiliac joint (SIJ) dysfunction. Injection of a painkiller into the SIJ relieved symptoms, including groin tenderness. Symptoms improved gradually, and finally disappeared after five SIJ injections. Groin pain has been reported as a referred symptom of SIJ dysfunction in 9.3-23% of patients. Prior to the patient undergoing surgery to treat lumbar spondylolisthesis, SIJ dysfunction had not been noted on physical examination. Long periods spent in the abnormal posture due to lumbar spondylolisthesis induced SIJ stress. After the operation, an improvement in daily activity actually increased stress on the SIJ, resulting in SIJ dysfunction. Certain pathologies, including SIJ dysfunction, should be considered as residual symptoms after operations for lumbar spinal diseases.