The purpose of this report is to describe our experience with the posterior interspinous fusion in the treatment of spinal injury with quadriplegia. The charts and roentgenograms of 22 patients treated with this operation by the senior author (RW) from July 1978 to June 1981 were reviewed retrospectively. Follow-up averaged 19.5 months. All injured spines had significant posterior ligamentous damage. There were 14 fracture-subluxations, two unilateral facet dislocations, and six bilateral facet dislocations. The specific operative indications included six unacceptable closed reductions, nine failures of three-month trials in a halo vest, and seven cases of predominantly ligmentous injury. All fusions were solid by the third postoperative month. There were no nonunions. There was horizontal translational deformity (2.0 and 3.0 mm, respectively) within the fusion in two cases. In one case, there was an 18° kyphosis within the fusion. Flexible kyphosis adjacent to the fusion, which averaged 16°, was seen in five cases. The overall rate of neurologic recovery for this group was 32%. No patient lost function. Eliminating those patients who were complete quadriplegics preoperatively, the neurologic recovery rate was 77%. In comparison with the other treatments for cervical instability, posterior interspinous fusion is seen to be safe and effective.