In order to determine the occurrence of epiphytic toxic dinoflagellates in the coastal waters of San Andres Island, Caribbean Colombia, we analyzed the seagrass beds on the northern and eastern sides of the island. We found seven species of toxicogenic dinoflagellates, belonging to the genera Prorocentrum and Ostreopsis. The cell densities were generally low if compared with previous studies in other Caribbean sites, ranging from 0 to 836 cells/dry weight. The species encountered are known to produce toxins causing the Diarrehic Shellfish Poisoning and Ciguatera, poisonings which have been documented in the island.