Objective To investigate the difference between straight wire appliance and edgewise appliance treat-ment outcome. Methods 80 cases finished with two-arch straight wire or edgewise appliance between 1994 and 2001 were selected. The PAR index on pre- and post-treatment dental casts and PAR score was recorded respec-tively. According to the same pre-treatment PAR score and extraction pattern, the samples were divided into two groups, straight wire group and edgewise group, and each group had 40 cases. The data were analyzed statistically. Results Estimated with the post-treatment PAR score of posterior teeth alignment, the treatment with straight wire appliance was lower than that with edgewise appliance（Pthan edgewise appliance. Conclusion As for the posterior teeth alignment, the straight wire appliance was more accurate, and the straight wire appliance was more efficient than edgewise appliance.
