The purpose of this study was to probe the influences of krill (Euphausia superba) meal with NaF oral administration on a dose-effect relationship between fluoride levels of krill meal and serum enzyme activity such as alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) in rats fed experimental diets for 5 weeks. There were no significant decreases in the activities of ALP, AST, ALT, and LDH in sera among krill meal diet groups (KF10, KF20, KF30). However, these groups were significantly (p<0.05) lower enzyme activities than normal diet (ND) plus NaF 10 mg group (NF). The fluoride levels of serum and organ tissues (liver, brain, heart, lung, kidney) in NaF 10 mg groups (NF, KF10, KF20, KF30) were significantly increased by adding krill meal in comparison with normal diet group. The results indicate that a difficult to found toxicity to the tissues from krill meal diet groups.