Baseline studies to evaluate the role of different anopheline mosquitoes as probable vectors of malaria in the Lacandon rainforest region in Chiapas (México) were carried out in 3 rural villages between June and November 1988. Anopheles vestitipennis was the most abundant species in all the villages, followed by An. albimanus, An. punctimacula and An. darlingi. Human bait collections showed that An. vestitipennis and An. albimanus tended to bite man either indoors or outdoors, while An. punctimacula preferred to bite outdoors. Monthly man-biting rates of An. vestitipennis tended to follow the rainfall pattern. Plasmodium vivax was detected in An. vestitipennis only, with an estimated overall infection rate of 4.67 per 1000 mosquitoes (range 0-54.42, of 3500 mosquitoes assayed). This is the first incrimination of An. vestitipennis as a probable vector of P. vivax in México.