Objective To investigate the expression of P-21 activated kinase 1 (PAK1) and v-raf murine sarcoma viral oncogene homolog B (BRAF) V600E mutation in papillary thyroid carcinoma (PTC)and their relationship with clinicopathological characteristics.Methods Immunohistochemistry was used to detect the expression of BRAF V600E mutation and P-21 activated kinase 1 (PAK1) in 55 PTC tissues and 25 benign thyroid tissues.The correlation between their expression and clinicopathological characteristics were analyzed.Results BRAF V600E mutation and PAK1 expressed differently between PTC and benign thyroid (respectively,x2 =12.121,9.950,all P ＜ 0.01).The expression of PAK1 and BRAF V600E mutation was positively and significantly correlated with tumor invasion,grades and lymph node metastasis(P ＜ 0.05),but it had no correlation with age,gender,tumor size,multiple tumor foci and bilateral tumor foci in PTC (P ＞ 0.05).Expression of PAK1 in BRAF V600E negative PTC was higher than that in BRAF V600E positive PTC,and expression of PAK1 and BRAF V600E mutation in PTC were negatively correlated(r =-0.284,P ＜ 0.05).Conclusion Overexpression of either BRAF V600E mutation or PAK1 predicts poor prognosis of PTC patients.