This paper aims to present our experience of 7 cases of spastic children, using sonoelastography in assessing the muscle spasticity: the relaxed muscle structures appear mostly soft (green-yellow-red), while contracted or degenerated muscle fibers appear hard (blue). Using sonoelastographic findings we established the proper place for injecting the botulinum toxin (20 U/kg Dysport) into the affected muscle. The result was a precise, guided injection, with positive, therapeutic results. It is important consider several factors that can influence the evolution of the case: gray scale ultrasound appearance of the muscle, the patient age, the dosage and the fractionation of toxin.