A taxonomic study was carried out in July 2017 during a sampling campaign at a station in the Haouzia Bay of El Jadida, open on the Moroccan Atlantic coast and located two miles from the port of El Jadida. In this work, we presented for the first time an inventory of the Dinoflagellates phytoplankton of Haouzia Bay, El Jadida. A specific richness of 57 dinoflagellate taxa was noted. Most taxa were illustrated by micrographs based on light microscope observations. The taxonomic list of dinoflagellates was used to identify specific species known to possess potential toxicity effects, including Dinophysis spp < em>., Alexandrium spp < em>., Gymnodinium catenatum, Lingulodinium polyedra, Gonyaulax spp., or harmful effects, including Prorocentrum micans, Gyrodinium spirale, Scrippsiella trochoidea, among others.