Several studies in the Sea of Japan have dealt with the taxonomy, morphology and ecology of Chaetoceros species. In this study, a total of 33 Chaetoceros taxa was recorded between 1991 and 2004 from the phytoplankton of Peter the Great Bay, in the northwestern part of the Sea of Japan. This investigation was based on light and electron microscopy. Chaetoceros minimus is a new record for the Pacific Ocean, C. compressus var. hirtisetus is a new record for the seas of Russia, and C. socialis f. radians is a new record for the northwestern Sea of Japan. Diagnostic descriptions, illustrations and distribution are provided for all 33 Chaetoceros taxa from the study area.