The occurrences of harmful algal blooms in Indonesian waters have been increasing since the beginning of the first red tide programme in this country in 1991. Some of the blooms have caused illness and even death of people and also environmental deteriorations and economic losses in fisheries. The number of red tide species and distribution of those species also increased coincident with the raising number of investigations and trained people which existed in every province of this country.

Some species found have been observed as red tide maker and some of those are known as toxic species. Most of toxic species found are belonging to the dinoflagellates, however, only a few have caused bloom phenomena such as Pyrodinium bahamense var. compressum and Alexandrium affine. The most frequent species which have caused red tide phenomena in certain areas were belonging to the cyanobacteria, mainly Trichodesmium erythraeum, dinoflagellate Noctiluca scintillans and diatom Chaetoceros spp. The outbreaks of those species appeared occasionally in certain areas. The list of HAB species that have been recorded in Indonesian waters since the beginning of the programme is as follows: Pyrodinium bahamense var. compressum, Gymnodinium catenatum, Alexandrium affine, A. minutum, Gonyaulax spinifera, Dinophysis caudata, D. rotundata, Noctiluca scintillans, Prorocentrum lima, Gambierdiscus toxicus, Pseudo-nitzschia pungens, Chaetoceros convolutum,C. concavicorne, Trichodesmium erythraeum and T. thiebautii. The occurrence and distributions of those red tide species in Indonesian waters will be discussed.