Leiomyosarcomas of the central nervous system are extremely rare; however they are becoming more prevalent in immunocompromised patients. The authors present MRI (Magnetic Resonance Imaging) of six cases of pathological proved leiomyosarcomas of the central nervous system in patients infected with human immunodeficiency virus. MR images of 4 cases of intraspinal leiomyosarcoma showed lobulated masses expanding multilevel of neural foramina with extradural and intradural extension, giving dumbbell appearance which mimic neurofibroma. Two cases of intracranial leiomyosarcoma revealed a mass at the left cavernous sinus involving prepontine cistern in one case and two lesions in the other case showing masses with dural based appearance at the region of the planum sphenoidale and the posterior aspect of the falx cerebri which mimiced a meningioma. The leiomyosarcoma should be included in the differential diagnosis of extra-axial CNS lesions in HIV-infected patients.