A field and laboratory study was conducted to determine some of the parameters relevant to malaria transmission by Anopheles mosquitoes in Dajabon Province, Dominican Republic. Although all 4 species occurring in the area, i.e., An. albimanus, An. crucians, An. grabhamii and An. vestitipennis, were included in the investigations, most of the work focused on the first and last named species because of their abundance. Gonotrophic cycles were determined to be 2.6 and 3.2 days for An. albimanus and An. vestitipennis, respectively. Mean parity rates for the 2 species were 37.3 and 20.7%, respectively, in outdoor samples. The human blood index, as determined by ELISA, was 0.08 for An. albimanus and 0.12 for An. vestitipennis. Only An. albimanus was confirmed positive for Plasmodium falciparum circumsporozoite protein, using ELISA. The vectorial capacity of An. albimanus was determined to be 0.019 and that of An. vestitipennis 0.005.