ABSTRACT Harmful Algal Blooms (HAB), are natural phenomena that are produced by the proliferation of phytoplankton potentially harmful to humans and for some ecosystem services (e.g., good water quality for use in aquaculture, availability of natural resources). In Chile, HAB events of Pseudo-nitzschia spp. and Alexandrium catenella are particularly relevant due to their potential toxicity. Although there are studies of the negative impact of these events, both the prediction of the occurrence of these phenomena and the associated risks are limited in the country. The proliferations have been attributed to the action of various oceanographic forcings (e.g., vertical stratification, irradiation, availability of nutrients). A research has been made about the factors and processes that have been associated with the appearance, permanence and toxicity of HAB and about the methodological efforts made to study and generate HAB forecasts in other countries. Based on a compilation of the information of occurrences and localities affected by these events, the seasonal, interannual and spatial variability of the events or occurrences of HAB in Chile was constructed. Subsequently, the current monitoring system is described, as well as future prediction efforts. Finally, the configuration of a monitoring system with observations and integrated prediction for the occurrence of Pseudo-nitzschia spp. and Alexandrium catenella is suggested.