A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether use of the Hepcon point-of-care coagulation monitor (Medtronic, Minneapolis, MN) to optimise and monitor heparin and protamine dosage for cardiopulmonary bypass could decrease bleeding and blood and blood product requirements in adult patients undergoing cardiac surgery. Altogether 680 papers were identified on Medline, and 879 on Embase using the reported search strategy. Two further relevant papers were found by hand-searching of reference lists. Fourteen papers represented the best evidence on the topic. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses were tabulated. We conclude that in patients undergoing cardiac surgery, use of the Hepcon coagulation monitor will increase the dose of heparin but decrease the dose of protamine administered compared to more empirical ACT-based dosing regimes. There is some evidence that this leads to less activation of the coagulation system and may be associated with decreased postoperative bleeding and blood product requirements but more work is required to quantify the magnitude of this effect.