Ｏｂｊｅｃｔｉｖｅ　To investigate the association between the levels of the light-chain of neurofilament protein in the cerebrospinal fluid and plasma, and postoperative delirium (POD) in aged patients undergoing hip-replacement.　Methods　One hundred and sixty-seven patients with ASAⅠ-Ⅲ, aged 65-84 y, scheduled for hip-replacement surgery under subarachnoid anesthesia were enrolled. POD was screened postoperatively with the confusion assessment method once per day for five days. Cerebrospinal fluid and whole blood were collected to measure the levels of the light-chain of neurofilament protein. Additionally, other related risk factors for POD were also recorded.　Results　POD occurred in 22.6% of all surgical patients with confusion assessment method. Cerebrospinal fluid and blood levels of the light chain of neurofilament protein in the POD group were significantly higher than those in the Non-POD group (P<0.05). Logistic regression analysis showed that advanced age and lower preoperative Mini-Mental State Examination(MMSE) score were two independent risk factors for POD. However, no difference was observed in gender, weight, educational level, ASA classification, surgical time, and blood loss between POD and non-POD groups (P>0.05).　Conclusions　Preoperative cerebrospinal fluid and plasma levels of the light chain of neurofilament protein were associated with POD, thus may serve as a useful biomarker for the prediction of POD.