Neurocysticercosis (NCC) has been associated with a high frequency of DNA damage in human circulating lymphocytes and more recently with the development of hematological malignancies. Chronic inflammation, a common feature of helminthic infections, has been proposed to play a key role in carcinogenesis induced by parasites. However, this mechanism is more likely to occur during local tumorigenesis rather than in systemic neoplasia such as that reported for patients with NCC. As an alternative, constant antigen stimulation, which is a feature of chronic NCC, may increase the frequency of aberrations in chromosomes that harbor regions constantly rearranged during T and B lymphocyte maturation, e.g. chromosomes 7 and 14. Therefore, in this study we determined the frequencies of aberrations in chromosomes 7, 11 and 14 in lymphocytes from 10 NCC patients and 10 controls and compared them with the frequency observed in chromosomes 1, 2 and 4 in the same cell samples. Chromosome aberrations were analyzed using a chromosome painting technique. Although the genome painted by probes for chromosomes 1, 2 and 4 was almost twice as large as that painted by probes for chromosome 7, 11 and 14, translocations involving the later (median 7.6 per 1000 metaphases) were more frequent than those occurring in chromosomes 1, 2 and 4 (median 2.5 per 1000 metaphases, P = 0.002). These results suggest that persistent antigen stimulation can cause chromosome instability in lymphocytes from patients with NCC and should be considered as an additional mechanism whereby parasites may induce cancer.