The localisation of metastasis in muscle is rare and is discovered mainly during autopsy. Skeletal muscle metastasis may occur in the case of leukaemia, lymphoma, melanoma, thyroid, gastrointestinal tract and breast carcinoma. However the most frequent aetiology is lung cancer. We describe the case of a 67-year-old woman, suffering from epidermoid lung carcinoma localised in both upper right lobes, treated surgically with success. Two months after surgery, she complained of pain and a sensation of swelling in the adductor muscles of the left hip with important restriction of mobility. A MRI scan of the hip showed an ovoid mass between the obturator externus and the adductors muscles on the left side. Biopsy of the infiltrated muscles showed proliferation of carcinomatous tissue.