Objective To investigate the whether miR‐125b expression having the abnormality in nasopharyngeal carcinoma tissues and serum and whether having the correlation with the sensitivity of cisplatin chemotherapy .Methods The intact medical records and tissue and serum samples in 34 cases of clinically diagnosed nasopharyngeal carcinoma were collected and the serum samples in 34 individuals undergoing the physical examination were also collected as the controls .The expression of miRNA‐125b in carcinoma tissue ,paracancerous tissue and serum was detected by real‐time quantitative polymerase chain reaction (real‐time qPCR) .The statistical analysis was performed .Results The expression of miRNA‐125b in carcinoma tissue was significantly lower than that in paracancerous tissue(P=0 .006) ,and serum miRNA‐125b expression in nasopharyngeal carcinoma patients was signifi‐cantly lower than that in the individuals undergoing the healthy physical examination(P=0 .000);but the miRNA‐125b expression had no correlation between the paracancerous tissue and serum(r=0 .112 ,P=0 .528) .The expression of miRNA‐125b in cancer tis‐sues was correlated with the pathological typing ,T staging and N staging(P<0 .05) ,the serum miRNA‐125b expression in carcino‐ma subjects was only related with the N staging (P<0 .05) .The expression of miRNA‐125b in carcinoma tissue was negatively cor‐related with the sensitivity of cisplatin chemotherapy (P< 0 .05) ,however ,there was no obvious correlation between the serum miRNA‐125b level and the sensitivity of cisplatin chemotherapy (P>0 .05) .Conclusion The low miRNA‐125b expression may be involved in the occurrence and development of nasopharyngeal carcinoma and plays a certain significance for the diagnosis ,pathology typing and classification of nasopharyngeal carcinoma .Its expression level in cancer tissue can serve as one of indicators for screen‐ing out the cisplatin chemotherapy sche.