Pyrodinium bahamense var. compressa collected in Palau was confrmed to contain parain paralytic shellfish poisons at a high level of 1.5×10^-4 MU/cell. The persence of gonyautoxin V(GTX₅), neosaxitoxin (neoSTX), and two unidentified toxins cded tentatively as PBT₁ and PBT₂ were confirmed vut gonyautoxins I-IV were undetectable, in contrast to Protogonyaulax spp. Moluscs were found to be highly infested by the toxins. The folowing toxins wer identified: GTX₅, neoSTX, STX, and PBT₁ in Spondylus buteri; GTX₅, STX, and PBT_i, in Tridaxna crocea; GTX₃, neoSTX, STX, and PBT₁ in Spondylus bilocularis. In these bivales, however the proportion of GTX₅ and neoSTX was decreased while that of STX was increased. The population of P. bahamense var. compressa was relatively high insid Arumizu Bay, Korol, but was low outside the bay.