The reproductive phenology and epiphytic macroalgae of Sargassum muticum were studied through an annual cycle (September 1987 to November 1988 at two sites on the northwestern coast of Baja California, Mexico, which were subjected to different degrees of wave exposure . Sargassum muticum is a brown alga of Japanese origin, now considered a permanent member of the marine flora of Baja California. A similar reproductive development was observed at both sites, with a maximum percentage of reproductive plants from May to July (spring-summer) and minimum from December to March (winter) . Reproductive plants were found throughout the year . A total of 48 species of epiphytes were identified and seasonal variation in their diversity was observed . The greatest diversity was found at the more protected site .