We examined peritoneal cells of 16 marine teleost species to examine whether unique peritoneal cells observed in red sea bream are present in other marine teleosts or not. Thecomponents of peritoneal cells were divided into four types; I) consisted only of macrophages; II) two kinds of cells, macrophages and heterophilic granulocytes; III) three kinds of cells, macrophages, heterophilic granulocytes, and unclassified large round cells (large cells); and IV) four kinds of cells, macrophages, heterophilic granulocytes, large cells, and small cells with pyknotic nuclei. The group of type I included Japanese whiting, yellowtail, and Japanese conger. Group II included sea bass, rabbitfish, greenling, Japanese flounder, and filefish. Group HI consisted of red sea bream, wrasse, mackerel, common Japanese goby, and kitefin dragonet. Group IV included black sea bream, silver bream, and flathead. Small cells of flathead had a similar morphology to lymphocytes, when examined electron microscopically. As the large cells of group III and IV varied widely in morphologies, especially in nuclei and granules, we could not categorize the ‘large cells’ into a single cell type.