The effectiveness of Cotrel-Dubousset (CD) instrumentation in long fusions to the sacrum for adult spinal deformity was evaluated in 27 consecutive patients. The CD system provided acceptable correction of kyphosis and scoliosis while restoring or maintaining lumbar lordosis. However, the standard CD pelvic fixation using sacral pedicle and alar screws was problematic. Instrumentation-related complications were frequent (70%). Sagittal and frontal plane balance was difficult to achieve and not consistently maintained. The CD system using sacral pedicle and alar screws in the adult patient does not appear to offer advantages over alternative techniques for achieving arthrodesis to the sacrum for adult deformity.