During 1993, quarterly systematic samplings were made at ten representative locations of the benthic environments of La Paz Bay. At each location we gathered algae in the subtidal and intertidal zones. We identified 126 species, of which 118 were previously reported. Eight are first records: Amphiroa beauvoisii, A. misakiensis, A. vanbosseae, A. valonioides, Dictyota cervicornis, Endoplura aurea, Hydrolithon reinboldii, and Liagora ceranoides f. leprosa . The greatest richness was at Calerita and the smallest at Isla Gaviota. The largest number of species was found in spring and the least in autumn. In La Paz Bay the phycofloristic similarity between locations was determined by the degree of exposure to surge, depth, and type of substrate. The association analysis allowed us to identify groups of species that included organisms with different morphological characteristics, from structurally simple to complex, but that share a common preference for the same type of substrate and environment. The morphology of the algae that constituted the associations was different, however the organisms had strategies to adapt, allowing coexistence in habitats with similar conditions. La Paz Bay has a great variety of environments, different types of substrates, and climatic and oceanographic conditions which change during the year. In this sense, seaweeds would be a quantitative and qualitative sign of certain environmental characteristics. If the conditions change, there will be a variation in the species expression, which can be in number or in external morphology. This will depend on their ability to adapt.