The OBIS HAB node is a thematic node compiling and processiong data on occurrence of toxin producing micro-algae species and their impacts on ecosystems and human activity. The node covers the species included in the IOC-UNESCO Taxonomic Reference List of Harmful Micro Algae at http://www.marinespecies.org/hab/index.php. It is supported by a network of editors covering specific regions. In a first phase the editors are primarily harvesting the literature for known occurrences in order to have a base line data set in OBIS on toxic microalgae which will serve to validate occurrence data from larger data sets and time series in OBIS. This specific data set on toxic micro-alge will provide an important data basis for the first Global Harmful Algal Bloom Status Report.