In general, the present invention relates to a two-phase method for forming an autologous bioadhesive sealant composition or fibrin glue wherein all of the blood components for the bioadhesive sealant are derived from a patient to whom the bioadhesive sealant will be applied. First, a platelet rich plasma and a platelet poor plasma are formed by centrifuging a quantity of anticoagulated whole blood that was previously drawn from the patient. The platelet rich plasma and platelet poor plasma are then divided into two portions. To the first portion, which is used in phase-one, a compound that reverses the effect of the anticoagulant is added, and a clot is allowed to form. The clot is then triturated and the resulting serum, containing autologous thrombin, is collected. The serum obtained from phase-one is then mixed with the second portion of the platelet rich plasma or platelet poor plasma, used in phase-two, to form the bioadhesive sealant of the present invention.