The relationship between Cd and PO4 in the Kuroshio and Oyashio regions and the Okhotsk Sea was examined. The resultant equations are as follows: Cd (ng l−1)=37.0 PO4 (μM)+2.6; Cd(ng l−1)=32.1 PO4 (μM)+1.2 and Cd (ng l−1)=34.1 PO4 (μM)+7.9, respectively. These results are in good agreement with previously reported studies, and indicate that during removal from surface waters to deeper waters by biological assimilation and regeneration in deeper waters Cd and PO4 maintain the same ratio in the open ocean. The relationship between Cd and PO4 in coastal waters, however, differed from that in the open ocean.