Objective To explore the expression of matrix metalloproteinase （MMP）-2 in patients with papillary thyroid cancer （PTC） recurrence or residuum and its value of clinical application. Methods The serums from 68 patients with thyroid disease underwent operation and 15 health examinations under stomachs empty from March 2009 to December2009 in this hospital were gathered. Sixty-eight patients with thyroid disease were divided into PTC with lymph node metastasis （LNM） group （n=19），PTC recurrence or residuum with LNM group （n=17），PTC without LNM group （n=10），and benign thyroid disease group （n=22） according to the postoperative pathological findings，15 health examinations as control group. The expression of MMP-2 of serum sample was detected by ELISA method. The difference of the expression of MMP-2 in each group was analyzed. Results The expressions of MMP-2 in the PTC recurrence or residuum with LNM group，PTC with LNM group，PTC without LNM group， benign thyroid disease group，and the control group were （1 724.00±762.24） ng/ml，（1 329.16±776.59） ng/ml，（1 489.61±546.53） ng/ml，（1 264.87±817.27） ng/ml，and （608.43±88.63） ng/ml，respectively. The expressions of MMP-2 in the PTC with LNM group and PTC recurrence or residuum with LNM group were significantly higher than those in the benign thyroid disease group （P＜0.05） and the control group （P＜0.05），respectively，which in the PTC without LNM group was significantly higher than that in the control group （P＜0.05）. There was no significant difference of MMP-2 expression of serum between the benign thyroid disease group and the control group （P＞0.05），which were no significant difference among the other threemalignant disease groups （P＞0.05）. The MMP-2 positive expression rates were 79%，76%，80%，41%，and 20% in the PTC with LNM，PTC recurrence or residue with LNM group，PTC without LNM group，benign thyroid disease group，and control group，respectively. The MMP-2 positive expressions rates of serums were not significantly different among three malignant disease groups （P＞0.05），but which were significantly higher than those of the benign thyroid disease group （P＜0.01） and control group （P＜0.01），respectively. Conclusions The MMP-2 level of serum can be used as an index to judge preoperative thyroid nodules，which can not be use to determine whether PTC metastasis or not.