To the Editor. —Two recent reports 1,2 have cast some doubts on the efficacy of praziquantel in the treatment of neurocysticercosis. Because this disease is an important neurosurgical problem in Latin America, we wish to report briefly on our experience with this drug. The introduction of computed tomography (CT) and immunofluorescence have greatly expanded our diagnostic capability with this disease at about the same time that praziquantel, a synthetic acylated isoquinoline-pirazine derivative, graduated from veterinary to human use. During the past three years, we have treated 47 patients with cysticercosis of the CNS. The initial clinical signs and symptoms consisted of increased intracranial pressure in ten patients, epileptiform seizures in 28 patients, mental changes in five patients, combinations of the above in three patients, and ocular manifestations in one patient. All of these patients tolerated the praziquantel therapy well, with the following complications being observed: mental changes in three patients