A 48-year-old male patient complained of pain in his left leg and ankle since he had RT-PCR COVID-19 diag nosis - three months before, which became unbearable in the last hours. There was no limitation of movement of the affected limb during the period. He had a three-dose COVID vaccination and denies sports practice and trauma. On physical examination, there was significant leg and ankle swelling with intense pain on palpation in the anterior region of the leg, with no change in skin col oration or in temperature. Arterial and venous Doppler ultrasound of the lower limbs did not detect thrombo sis. MRI detected compartment syndrome of the ante rior compartment of the leg (Fig. 1, arrows). The patient was immediately treated with fasciotomy of the anterior compartment of the leg, which showed an area of necro sis and an acute inflammatory process in the affected musculature, confirmed by biopsy. The patient recovered well, with a warm and well-perfused lower limb. He was discharged from the hospital two days after the surgery and referred for outpatient follow-up without sequelae. Myositis caused by COVID-19 is highly atypical, occurring through direct invasion of myocytes or induced by auto immune pathways. Its presentation ranges from overt muscle weakness to typical dermatomyositis with classic skin rashes or solely pain with muscle involvement on MRI.