Abstract:[Objective]To detect the difference of the expression of microRNA-613(miR-613)in papillary thyroid carcinoma(PTC),nodular goiter and normal thyroid tissues surrounding the cancer,and to explore the significance of miR-613 in PTC.[Methods]A total of 190 cases of PTC undergoing thyroid resection,44 cases of distal non-tumor normal thyroid tissue surrounding the cancer and 3 1 cases of nodular goiter in our hospital from March 2012 to Sept.2013 were collected.The expression level of miR-613 in PTC tissue,normal thyroid tissue surrounding the cancer and nodular goiter tissue were assayed by real-time polymerase chain reaction (PCR).The correlation between miR-6 1 3 expression and clinicopathologic features of PTC was analyzed.[Re-sults]The expression level of miR-6 1 3 in PTC tissue was obviously lower than that in non-tumor tissue(P<0.05),but there was no significant difference among non-tumor tissues(P>0.05).The expression level of miR-613 was correlated with extra-thyroid invasion of PTC(P<0.05).[Conclusion]The expression level of miR-6 1 3 in PTC is decreased and correlated with tumor invasiveness.