Background Total knee replacement (TKR) is a common and o en painful operation. Femoral nerve block (FNB) is frequently used for postoperative analgesia. Objectives To evaluate the benefits and risks of FNB used as a postoperative analgesic technique relative to other analgesic techniques among adults undergoing TKR. Search methods We searched the Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 1, MEDLINE, EMBASE, CINAHL, Web of Science, dissertation abstracts and reference lists of included studies. The date of the last search was 31 January 2013. Selection criteria We included randomized controlled trials (RCTs) comparing FNB with no FNB (intravenous patient-controlled analgesia (PCA) opioid, epidural analgesia, local infiltration analgesia, and oral analgesia) in adults a er TKR. We also included RCTs that compared continuous versus single-shot FNB. Data collection and analysis Two review authors independently performed study selection and data extraction. We undertook meta-analysis (random-e ects model) and used relative risk ratios (RRs) for dichotomous outcomes and mean di erences (MDs) or standardized mean di erences (SMDs) for continuous outcomes. We interpreted SMDs according to rule of thumb where 0.2 or smaller represents a small e ect, 0.5 a moderate e ect and 0.8 or larger, a large e ect. Main results We included 45 eligible RCTs (2710 participants) from 47 publications; 20 RCTs had more than two allocation groups. A total of 29 RCTs compared FNB (with or without concurrent treatments including PCA opioid) versus PCA opioid, 10 RCTs compared FNB versus epidural, five RCTs compared FNB versus local infiltration analgesia, one RCT compared FNB versus oral analgesia and four RCTs compared continuous versus single-shot FNB. Most included RCTs were rated as low or unclear risk of bias for the aspects rated in the risk of bias Femoral nerve blocks for acute postoperative pain a er knee replacement surgery (Review)