Laboratory tests showed that 2 strains of Anopheles albimanus Wiedemann. When given a choice of oviposition medium of 0, 25, 50, or 100% sea water, laid ca. 40% of their eggs in fresh water, but laid ca. 10% in pure sea water. Subsequent laboratory rearing showed that higher salt content of the rearing medium definitely reduced the development and survival of both strains in the immature stages, but 1 strain produced pupae in water with as high as 15.075 parts per thousand (ppt) salt. The salinity of the medium did not significantly affect percentage emergence in either strain of those insects that reached the pupal stage. Since high salinity affects larval development in the laboratory, we could expect the same to be true in estuarine habitats. However, field observations suggest that breeding in brackish water probably is associated with the presence of favorable breeding sites in areas with much vegetation, rather than with the reduced salinity of the water.