The overall proportion of sera with antibodies against cyticercus antigens in 3226 serum samples collected among the Indian rural population in the proximity of San Cristóbal de Las Casas, Chiapas, México is 0.49. The proportion of positive sera varied from 0.4 to 7.6% inversely with the number of inhabitants in the community. The global proportion of positive sera in Chiapas being considerably lower than that expected from the autopsy frequency of brain cysticercosis in México City (1.4-3.6%), it is perhaps indicative of different epidemiologic dynamics in rural and urban areas.