The pan-Mediterranean project M3-HABs regarding monitoring of harmful algal blooms, with particular reference to the benthic dinoflagellate Ostreopsis, started in 2014 in the framework of the ENPI-CBCMED Programme. The specific objective of the project was to provide a common strategy for monitoring benthic toxic microalgae, through the development of new, more efficient and common procedures and protocols, making the process mostly cost and time effective, allowing for most efficient monitoring designs, increasing the knowledge on environmental drivers affecting Ostreopsis blooms and translate this into a forecasting tool, and improving the general awareness of the risks related to Ostreopsis. The following results were obtained: a larger awareness of the risks associated with the Ostreopsis blooms, an appropriate diffusion of cautionary measures set up, the production of common monitoring protocols, the development of new technologies for species-specific identification and counting and the build-up of prediction models in order to prevent and reduce risk factors for the environment, human health and economic activities. The project improved the establishment of solid networks along Mediterranean coasts to cope with Ostreopsis emergencies, providing the target groups common and intercalibrated protocols, in order to have comparable samplings in space and time through the Mediterranean Sea.