The aim of this study is to report on the growing frequency of neurocysticercosis (NCC) in Madrid (Spain) related to changes in migratory flows. We investigated the origin of 20 patients with NCC seen over a period of 13-years (1990- 2002). Patients age and disease activity were compared with a second group of 13 patients observed in the same hospital in 1980-1989. Eighty per cent of the patients observed in the first group were foreign immigrants, all but one from South-American countries. They were young (mean age: 31.4 +- 7.7 years) and most had evidence of active disease. In contrast, only 15 % of the 13 patients observed during 1980-1989 were foreign immigrants. Recently seen Spanish-born patients were elderly (mean age: 67.3 +- 2 years), had emigrated many years earlier from rural areas where the disease was formerly prevalent, and had inactive forms of the disease. We conclude that the recent increase in the frequency of NCC in Madrid reflects a rapid growing of immigrant population from countries where the disorder is highly prevalent. Transmission of the parasite from asymptomatic T. solium carriers represents a challenge to disease prevention. Our observations should alert other European countries that may become potential destinations for similar inbound migratory flows.