The computed tomography findings in 27 patients with an ultimate diagnosis of femoral neuropathy were reviewed. Haemorrhagic disorders were responsible for the neuropathy in 10 patients, neoplasia in eight, infection in five and in the remaining four patients no abnormality was noted on CT and the aetiology remained uncertain. Unilateral enlargement of the iliopsoas muscle or a soft tissue mass involving the iliopsoas compartment was noted in the 23 patients with positive studies. The exact nature of the mass could not be determined by CT alone, but, when considered together with clinical history and examination, a definitive diagnosis was possible in most instances. Whenever necessary, percutaneous needle biopsy or drainage was performed. Computed tomography should be performed at an early stage in all patients suspected of femoral neuropathy. It accurately demonstrates and delineates retroperitoneal masses causing this condition and allows further definitive diagnostic procedures such as biopsy or drainage to be performed when necessary.