The wild dinoflagellate Alxandrium minutum was collected from the coastal area and aquaculture pond in Yapu Aqueduct, southern Taiwan from February 1996 to April 1997. It was found the toxic dinoflagellate A. minutum appeared from December to March. HPLC analyses showed that the toxins from the coastal area were GTX 3 (96.8%), GTX 2 (3.2%), GTX4 (0.2%), STX (0.1%), and neoSTX (0.1%), while toxins from the aquaculture pond were GTX 3 (96.3%), GTX 2 (3.4%), GTX4 (0.3%), and GTX 1(0.1%). On the other hand, A. minutum T1 was isolated form an aquaculture pond in February 1996, and grown under various environmental and nutritional conditions. The optimal environmental condition for cell growth and toxin production of A. minutum T1 was as follows: temperature 25C, pH 7.5, light strength 6 x 10³ lux, and salinity 15 ppt. The optimal level of nutrients supplemented in the 50% natural seawater medium for those of A. minutum T1 was as follws: phosphate 0.002%, nitrate 0.01%, cupric ion 5.0 ppb, ferric ion 270 ppb, and humic acid free. HPLC showed A. minutum T1 contained GTX 1-4 only. Among these components, toxins 1,4 were the predominant compounds throughout the growth circle when the cells were grown in the optimal environmental and nutritional conditions. But toxins GTX 2,3 increased when the cells were cultured at high salinity medium.