Morel-Lavallée lesions tend to be misdiagnosed when patients present with soft tissue injury alone and are treated in an outpatient department. A 35-year-old woman presented with swelling over the posterolateral aspect of the thigh 3 months after sustaining an injury. Diagnosis of Morel-Lavallée lesion was made and confirmed by ultrasound examination. The walls of the lesion were debrided using an arthroscopic shaver (Stryker, Kalamazoo, MI), and intermittent suction therapy was applied to obliterate the dead space. This brief report demonstrates that this minimally invasive technique is effective in treating chronic Morel-Lavallée lesions.