Production of metabolites from microalgal dinoflagellates requires them to be grown in a controlled environment, usually as relatively large-volume pure cultures, in some form of a bioreactor. This chapter focuses on bioreactor culture of dinoflagellates. The dynamics of bloom development in coastal waters appear to be related more too oceanic flow patterns and winds that concentrate biomass in areas of low turbulence and less to any sudden increase in the growth rate of the cells. The production of gram quantities of Dinoflagellate bioactives for various purposes has mostly relied on culturing them in low-productivity systems. Studies of metabolite production in Dinoflagellate cultures have not generally used media optimized specifically for maximal productivity. Culture of dinoflagellates at any Significant scale inevitably requires the use of bioreactors and photobioreactors, depending on the nature of the production operation. Products such as docosahexaenoic acid have been produced via heterotrophic culture of nontoxic dinoflagellates in conventional fermenters.