Background: Point-of-care testing for hemoglobin (POCTHb) is increasingly used in the operating room to guide transfusions. The accuracy of POCT-Hb in surgery is, however, unclear, and inaccurate devices could lead to inappropriate transfusions. A systematic review and meta-analysis of method comparison studies assessing the accuracy of POCT-Hb versus central laboratory in patients undergoing surgery was performed. Embase, Ovid MEDLINE, and EBM Reviews were searched from inception to April 2020. Methods: Studies that compared hemoglobin measurements between POCT-Hb devices and central laboratory in patients undergoing any surgery in the operating room were included. The primary outcome was the mean difference (MD) between POCT-Hb and central laboratory (with standard deviation SD). Using a random-effects model, the population limits of agreement (95% LOA) were calculated as a function of the average difference between the 2 tests, the average within-study variation, and variation in bias across studies. Results: The allowable reference standard for hemoglobin measurement defined by the Institute of Quality Management in Healthcare (IQMH) is 4.0 g/L. Of 2377 identified studies, 32 were included (n = 2591 patients, 8476 hemoglobin paired measurements). Several devices were compared with central laboratory (pulse co-oximetry: 24 studies; Hem°Cue: 9 studies; iSTAT: 6 studies; blood gas analyzers: 9 studies; and hematology analyzer: 1 study). The median sample size was 40 paired measurements, 10 of 32 studies had manufacturer funding, and 15 of 32 studies were low risk of bias. The pooled MD (95% LOA) was 2.5 g/L (-28.2 to 33.1) for pulse co-oximeters, -0.6 g/L (-10.6 to 9.3) for Hem°Cue, -0.3 g/L (-8.4 to 7.8) for iSTAT, and -2.0 g/L (-16.5 to 12.5) for blood gas analyzers. The pooled intervals for POCT-Hb devices were all larger than the allowable reference defined by IQMH. Conclusion: Hemoglobin values measured by POCT devices cannot be considered interchangeable with central laboratory, and abundant caution is necessary when using these devices to guide transfusions in the operative setting.