<b><i>Objective:</i></b> A number of studies have evaluated the efficacy and safety of fondaparinux versus low-molecular-weight heparin (LMWH) in patients with acute coronary syndrome (ACS), but the findings were not consistent across these studies.<b><i> Methods:</i></b> Electronic databases and article references were searched for studies that assessed fondaparinux versus LMWH in ACS patients. <b><i>Results:</i></b> Six studies met the inclusion criteria. There was a lower risk of major adverse cardiac events (MACE) with fondaparinux-based regimens both in randomized controlled trials (RCT; risk ratio, RR: 0.91, p = 0.04) and observational studies (RR: 0.85, p < 0.0001). Mortality decreased in fondaparinux-treated patients in RCT (RR: 0.84, p = 0.02), but not in observational studies (RR: 1.44, p = 0.64). For the analysis of myocardial infarction (MI), recurrent ischemia and stroke, none of the studies showed significant results. In addition, fondaparinux lowered the risk of major bleeding in RCT (RR: 0.62, p < 0.0001) and observational studies (RR: 0.65, p < 0.0001). The net clinical outcome also favored fondaparinux over LMWH in RCT (RR: 0.82, p < 0.0001) and observational studies (RR: 0.84, p < 0.0001). <b><i>Conclusions:</i></b> Among ACS patients, a fondaparinux-based regimen presented advantages regarding MACE and major bleeding, and a net clinical benefit compared with LMWH, although the benefit is minimal regarding MACE. For death, MI, recurrent ischemia and stroke, fondaparinux has not shown significant benefits
