Currently, Taiwan lacks a systematic study on the effect of anti-dumping protection on the technical efficiency of Taiwanese firms. As such, in this study, all cases of anti-dumping complaints of companies listed in Taiwan during 1984 and 2010 are used to investigate the effects of anti-dumping complaints on the technical efficiency of Taiwanese firms. Our research results indicate that, although the average effect of anti-dumping complaints has a positive impact on the technical efficiency of complaining firms, there are still negative results in 30% of cases. Among them, anti-dumping protections can lead to great improvements in the low-technology manufacturers. However, if the protection time for these manufacturers is prolonged, their technical efficiency declines. Additionally, if the duration of imposed anti-dumping duties increases, it could also have the opposite effect. These results can serve as a reference for the government when presiding over anti-dumping complaints.