Purpose. To present clinical observation of a patient with muscle hernias and compare the possibilities of ultrasound and MRI methods for their diagnostics.

Materials and methods. The clinical observation of a 42-year-old male patient with history of insignificant pain in anterolateral aspect of distal third of the right leg in running was de-scribed in the article. A clinical and radiological examination including ultrasound and MRI was provided.

Results. In clinical examination a non-tender soft tissue mass, measuring 1.5 cm, more obvious in muscle contraction was revealed. Ultrasonogram examination showed small focal bulging mass, isoechoic to the rest of the muscle. MRI demonstrated focal bulging mass originating from peroneus longus muscle. Another small muscle hernia at the medial aspect of middle third of the right leg was also detected on MRI.

Conclusion. Muscle hernias of the lower leg are not so rare, especially in active young men. Clinicians should include muscle hernias in the list of differential diagnoses of chronic leg pain and neuropathy. Ultrasound is the preferred diagnostic method because it can be easily used for dynamic examination of a hernia, and define the nature of the mass. MRI can confirm the presence of muscle hernia and determine the hernial muscle and its size, exclude other causes of the mass and illustrate any fascial defects.