BackgroundPerioperative transfusion can reduce the survival rate in colorectal cancer patients. The effects of transfusion on the short- and long-term prognoses are becoming intriguing.ObjectiveThis systematic review and meta-analysis aimed to define the effects of perioperative transfusion on the short- and long-term prognoses of colorectal cancer surgery.ResultsThirty-six clinical observational studies, with a total of 174,036 patients, were included. Perioperative transfusion decreased overall survival (OS) (hazard ratio (HR), 0.33; 95% confidence interval (CI), 0.24 to 0.41; P < 0.0001) and cancer-specific survival (CSS) (HR, 0.34; 95% CI, 0.21 to 0.47; P < 0.0001), but had no effect on disease-free survival (DFS) (HR, 0.17; 95% CI, − 0.12 to 0.47; P = 0.248). Transfusion could increase postoperative infectious complications (RR, 1.89, 95% CI, 1.56 to 2.28; P < 0.0001), pulmonary complications (RR, 2.01; 95% CI, 1.54 to 2.63; P < 0.0001), cardiac complications (RR, 2.20; 95% CI, 1.75 to 2.76; P < 0.0001), anastomotic complications (RR, 1.51; 95% CI, 1.29 to 1.79; P < 0.0001), reoperation(RR, 2.88; 95% CI, 2.05 to 4.05; P < 0.0001), and general complications (RR, 1.86; 95% CI, 1.66 to 2.07; P < 0.0001).ConclusionPerioperative transfusion causes a dramatically negative effect on long-term prognosis and increases short-term complications after colorectal cancer surgery.