The relationships between concentrations (μg/g of tissue) and content (μg/organ) of the metals Fe, Zn, Cu, Mn, and Cd with seasonal changes in the weight of the hepatopancreas in the Japanese scallop Mizuhopecten yessoensis are studied. It is shown that, during a year, the weight of the hepatopancreas in the mollusk shows significant (more than twofold) changes. A positive correlation is revealed between the seasonal changes in the concentrations of the physiologically important metals Fe, Zn, Cu, and Mn and the weight of this organ, although no general consistent pattern of seasonal variability in the metal concentrations is found. For toxic Cd, a negative correlation is found between its concentration and the weight of the hepatopancreas.