Objective. To assess the radiological features of Morel-Lavallée effusion in the thigh. Design and patients. A restrospective study of clinical records and radiological studies was carried out on three patients with Morel-Lavallée effusion. Results and conclusions. Ultrasound and computed tomography (CT) were able to locate the effusion in the three patients. CT demonstrated a capsule around the lesion. A fluid-fluid level was visible with both techniques. Ultrasound and CT are good methods for assessing patients with Morel-Lavallée effusion of the thigh. CT can be used to distinguish patients requiring surgical treatment from those who could be treated by conservative measures.