Some metabolites related to Umami (Japanese flavor) in the adductor were measured after transfer of scallops from aerobic to anaerobic conditions for 12h. The cellular level of succinic acid increased linearly up to 12h in proportion to the accumulation of lactic acid, and was about 5 times higher than that in aerobic scallop. The ATP level did not show any significant change for the initial 3h, and then decreased rapidly. Changes in the ADP and AMP levels reflected those of ATP, and the AMP level was about twice as high as that in aerobic scallop at the end of acclimation. The arginine level decreased gradually in proportion to acclimation time. However, no striking decrease in other free amino acids, including glutamic acid, glycine and alanine, was found during acclimation. These results indicate that the increase of metabolites related to Umami is attained by transferring scallop to anaerobic conditions.