Fondaparinux is the first drug from the pentassaccharide factor X inhibitor class of anticoagulants to be approved for clinical use. It has been shown to be effective in the prevention of deep vein thrombosis in patients undergoing major orthopaedic surgery of the lower limbs. The drug is also being evaluated for use in the acute coronary syndromes and established thromoboembolic events. The pharmacology of fondaparinux is discussed in this review, as well as the major clinical trials involving this drug. Arguments for (and against) the use of this drug are also summarised.