The present invention relates to a method for dynamically determining the structural profile of a fibrin clot, reflecting the stability thereof in a biological sample of a patient, said method comprising the following steps: a) mixing the undiluted biological sample with tissue factor or a mixture of tissue factor and tissue plasminogen activator; b) incubating the mixture obtained in step a), then adding calcium ions to the mixture obtained, in order to initiate the formation of a fibrin clot; c) measuring the turbidity or the optical density of the clot being formed in step b), at at least two wavelengths of between 450 nm and 850 nm, and for a time of between 1 and 35 minutes; d) determining the structural profile of the analysed clot, expressed as a number of protofibrils, density and radius in c) by means of the formula τ.λ
5 = A [Fg].(λ
2 - B), wherein τ is the turbidity of the clot at a given wavelength λ, [Fg] is the initial weight concentration of fibrinogen, and A and B are coefficients which are proportional, respectively, to the density and the radius of the fibres that make up the clot; and e) comparing the obtained profile with a control. The method preferably includes a step f) that makes it possible to predict the risk of bleeding, thrombosis or rethrombosis and to select the anticoagulant that is best suited to the clinical situation of a patient.