The present invention relates to a method for measuring at least one viscoelastic parameter of a human or animal organ, said method having the following steps: emission of a plurality of ultrasonic shots by an ultrasonic transducer, said ultrasonic shots propagating in the organ that is to be characterized; reception by the ultrasonic transducer and recording of the reflected ultrasonic signals; determination of at least one viscoelastic parameter of the organ on the basis of the recorded ultrasonic signals; the plurality of ultrasonic shots is formed by K groups of shots, said groups being separated temporally, K being greater than or equal to 1; each of the K groups of ultrasonic shots is formed by the repetition, with a rate of PRF2, of MK blocks of ultrasonic shots, MK being greater than or equal to 1; each of said MK blocks is composed of N ultrasonic shots, N being greater than or equal to 1, PRF1 being the rate of emission of the N shots when N is chosen greater than 1; the N ultrasonic shots are distributed over P frequencies, P being between 1 and N, at least two ultrasonic shots belonging to two different blocks having different frequencies.