Marine dinoflagellates, one of the most important components in phytoplankton are receiving much attention owing to their toxicity. They are responsible for causing toxic blooms and associated poisonings such as Paralytic shellfish poisoning (PSP), Neurotoxic shellfish poisoning (NSP), Diarrhetic shellfish poisoning (DSP), Azaspiracid shellfish poisoning (ASP) and Ciguatera fish poisoning (CFP) in humans all over the world. However, recent research has shown that such toxins could be of great use therapeutically. Aspects such as the identification of dinoflagellate species; harmful dinoflagelllate blooms and associated poisonings as well as their bioluminescence and biotechnological applications have been dealt with in detail. A comprehensive book on marine dinoflagellates is hitherto wanted and needed, and it is hoped that the present publication would cater to the needs of students of life science disciplines in general and marine biology and fisheries science disciplines in particular.