The authors emphasize the low frequency of motor impairment with mono or hemiplegic distribution, due to cysticercotic lesions of the brain. It is also stressed the difficulty of the diagnostic problems posed by some of these cases. Two pathogenic mechanisms are pointed out: the paralyses caused by granulomatous brain foci, near or far from the parasite, and the cerebrovascular infarctions induced by the marked changes in blood vessels. Nineteen cases of cysticercosis of the central nervous system including 17 hemiplegic and 2 monoplegic forms are reported. In every case the etiology was established by a positive complement fixation test for cysticercosis in the cerebrospinal fluid, and was supported, in 2 cases, by suvgery and post mortem examination. Convulsions were referred by 10 patients (7 times focal and 3 generalized). Symptoms of intracranial hypertension were present in 4 patients. The hemiplegia set up like an ictus in 14 patients. In 3 cases the data were highly suggestive of a vascular pathogeny; in 3 the symptomatology was directly related to the parasitic granuloma, although the vascular disease must have shared in the process; in 1 the paralysis was probably post-epileptic; in 3, although subsidiary data were not sufficient, the clinical facts gave emphasis to the role of the vascular factor in the onset of the hemiplegia. In 5 patients the motor impairment was slow and progressive. In 2 cases cysticerci were found on the cerebral cortex and removed; the post mortem examination showed, in one of them, an ischemic softening of the parietal cortex contralateral to the hemiplegia; in 1 case there was cysticercosis of the nervous structures of the posterior cranial fossa, associated to a cortical lesion which induced severe electroencephalographic changes; 2 cases lacked subsidiary data which could help to disclose the pathogenic mechanism of the hemiplegia. The authors give emphasis to the possibility that, in some of these cases, the clinical data might have led to a wrong diagnosis, either of a brain tumor or of a cerebrovascular disease with unknown etiology. In such instances, the patients would be deprived of the eventual benefits of a proper treatment, either with drugs or surgery.