The clinical and experimental superiority of an autograft over an allograft has been well documented. The autografts are recognized as "self", whereas the allografts are recognized as "nonself", a consequence of genetic disparity between the donor and the recipient. Despite this lack of histocompatibility between the donor and recipient, allografts generally proceed to a satisfactory clinical result, although at a slower rate than autogenous grafts. This is ture for fresh as well as frozen bone, although preserved grafts require longer to induce the response and the reaction is usually less intense. The purpose of this study is to review the fusion rate and duration of a series of 95 consecutive patients who had posterolateral spine fusion with autogeneic vs. allogeneic bone graft. A total of 95 consecutive patients were operated upon from 1984 to 1988 using cancellous or corticocancellous chip graft in posterolateral fusion of the spine, comparing a frozen allograft to a fresh autograft. Frozen allografts were gained from femoral heads after total hip replacement and the autografts from posterior iliac crest. The mean follow-up time from surgery to evaluation was 19 months with a minimum of 12 months and a maximum of 38 months. The evaluation consisted of a review of the office chart, the hospital record, the pre- and postoperative roentgenograms, and a personal interview with the patient. In reviewing the 95 patients who had adequate postoperative roentgenograms, we found 89 solid arthrodeses and six nonunions, giving a fusion rate of 93.7%. Of the 48 patients treated by autograft, 97.9% obtained solid fusion as judged by roentgenograms. And of 31 patients treated by allograft, 87,1% fused. And of 16 patients treated by mixed, 93.8% fused. Using the one-way ANOVA test, we found that there was a statistically significant relationship(p<0.05) between the graft material and the fusion rate. In conclusion, these results suggest that antigenicity of the frozen allograft still inhibit grafted bone incorporation and required longer time periods to graft pone incorporation. On the other hand, the relatively high successful rate of the deep-freezing allograft is of value to the patient.