A method for characterizing an anisotropic soft medium (C) comprising at least one portion including fibers and having an outer surface , this method comprising the following steps: (a) a measurement step during which at least one shear wave is generated which propagates by diverging from a central area in the anisotropic soft medium and, a propagation of said at least one shear wave is observed with ultrasonic observation transducers , from the surface of the anisotropic soft medium, in several predetermined propagation directions (P) from said central area by maintaining fixed the ultrasonic observation transducers , said predetermined propagation directions (P) comprising at least two directions forming between them an angle different from 0 degree and different from 180 degrees, said ultrasonic observation transducers being positioned at least along said predetermined propagation directions (P) and said measurement step being carried out within a period of less than 50 ms; (b) at least one computing step during which at least one propagation parameter of the shear wave is determined, from data collected during the measurement step (a) in each of said predetermined propagation directions (P); (c) a characterization step during which, from said at least one propagation parameter of the shear wave, determined in each of the propagation directions (P) in the computing step (b), at least one rheological characteristic of the anisotropic soft medium is determined, selected from among a direction of the fibers of the anisotropic soft medium, a rheological elasticity parameter in a direction perpendicular to the fibers and a rheological elasticity parameter in the direction of the fibers. (a) a measurement step during which at least one shear wave is generated which propagates by diverging from a central area in the anisotropic soft medium and, a propagation of said at least one shear wave is observed with ultrasonic observation transducers , from the surface of the anisotropic soft medium, in several predetermined propagation directions (P) from said central area by maintaining fixed the ultrasonic observation transducers , said predetermined propagation directions (P) comprising at least two directions forming between them an angle different from 0 degree and different from 180 degrees, said ultrasonic observation transducers being positioned at least along said predetermined propagation directions (P) and said measurement step being carried out within a period of less than 50 ms; (b) at least one computing step during which at least one propagation parameter of the shear wave is determined, from data collected during the measurement step (a) in each of said predetermined propagation directions (P); (c) a characterization step during which, from said at least one propagation parameter of the shear wave, determined in each of the propagation directions (P) in the computing step (b), at least one rheological characteristic of the anisotropic soft medium is determined, selected from among a direction of the fibers of the anisotropic soft medium, a rheological elasticity parameter in a direction perpendicular to the fibers and a rheological elasticity parameter in the direction of the fibers. <EOS>