Thirty-five cases of cysticercosis, including 31 of neurocysticercosis, three subcutaneous and one ocular case, were studied and treated with praziquantel (PZQ). The three subcutaneous cases were cured within 2–3 months and the ocular case did not improve. In 31 patients with neurocysticercosis the diagnosis was made by specialized technics, including computerized tomography (CT) and hemagglutination test (HA). Four main clinical syndromes were found: epilepsy in 14, intracraneal hypertension (ICH) in seven, a combination of the two syndromes in seven and headache in three. Fourteen of these patients underwent surgery and in 11 of them cysts were removed. PZQ treatment was given to these patients to treat remaining cysts. Seventeen patients without prior surgery were treated with the drug. Among 29 cases with follow-up the following clinical results were observed: ICH and headache were cured in 13 of 15 patients, and in two cases there was improvement, epilepsy was under control in 14 of 19 cases receiving antiepileptic drugs; in four patients the seizures were still present, although less frequent and in one patient there was no improvement of the epileptic syndrome. Only one patient died. CT revealed cysticerci in different stages of development in each of 15 patients, as shown by the presence of two or more different patterns in all of them. All calcified lesions remained unchanged. In 11 cases that presented with non-calcified lesions and had CT before and after therapy, the lesions disappeared in seven, cysts were reduced in number or in size in two, and in the remaining two cases no changes were observed. HA was positive at significant titers of 1:128 or higher in 21 cases of the neurological disease (67%). The patients presenting with ICH showed in general higher titers. In 16 cases serum HA was done before and after treatment with the following results: in six the titers decreased, in three they remained unchanged, in four there were variations up and down, and in three cases the titers were raised. Blood and urine examinations before and after treatment did not reveal significant changes. Side effects were observed in 10 of 35 patients treated; symptoms were transient and of low intensity in five of them, consisting of headache, nausea and vomiting that did not require treatment. In the other five patients symptoms were more intense due to increase of the ICH, and parenteral steroids, and in one case mannitol, were required. It is concluded that praziquantel is effective in the treatment of cysticercosis, a disease that previously did not have a specific medical treatment. The mortality rate in this series of 31 cases of neurocysticercosis treated with PZQ was only 3.2%, which contrasts with previous 50–80% case fatality rate in the same Colombian institution.