Four dinoflagellates, Alexandrium cohorticula, Alexandrium sp., Gymnodinum catenatum, and Prorocentrum gracile were isolated from Ambon Bay, a small, semi-enclosed bay on the island of Ambon. The fifth species Pyrodinium bahamense var bahamense was isolated from Manila Bay in the Philippines. These species were cultured in natural and artificial media and at different irradiances (10 - 400 mol photon m-2 s-1). All species grow well in artificial medium. The maximum growth rate for these species ranged from 0.18 - 0.56 d-1. Prorocentrum gracile has the highest growth rate (0.56 d-1) when grown in L1 media. When Pyrodinium bahamense var compressum was grown in medium L1 plus soil extract from the mangrove area in Ambon Bay its growth rate was higher compared to other media. Gymnodinium catenatum showed an increase in growth rate when it was cultured in soil-enhanced media. The onset of light saturation (Ik) for all species studied is around 50 mol photon m-2 s-1. The Ik for Alexandrium cohorticula was 60 mol photon m-2 s-1, but this species still grew at irradiances, as low as 10 mol photon m-2 s-1. This study is the first to explore the ecophysiology of dinoflagellates from Indonesia.