The authors report a case of iliac muscle haematoma responsible for inguinal pain in a patient with Gaucher's disease type I. This exceptional cause of pain must now be considered side by side with the classical femoral head osteonecrosis and infectious coxitis. Magnetic resonance imaging appears to be the most sensitive and most specific examination for the aetiological diagnosis of hip pain in Gaucher's disease. In the absence of thrombocytopenia and franck abnormality of coagulation, the spontaneousness of the haematoma is discussed.