The invention relates to a method for determining a concentration of ligands in an analyzed sample. The inventive method consists in immobilizing receptors specifically boundable with said ligands on a support. At least one measured value of the occupation of the support surface by the receptors is determined by means of a sensor for the surface occupation. Afterwards, the sample is put in contact with the receptors. At least one measured value of the frequency of liaisons between the ligands and the receptors is determined by means of at least one detector. The concentration of ligands in the sample can be determined with the aid of the measured values of the occupation of the surface and frequency of ligands/receptors liaisons.