This study was conducted to investigate the attractant substances of different solvent fractions of mackerel and tuna viscera. Mackerel and tuna viscera were extracted with methanol and the resultant were fractionated with n-hexane, chloroform, ethyl acetate, n-butanol and water. The chemical compounds such as free amino acid, fatty acid, nucleotide related compounds contents were estimated for mackerel, tuna viscera and various fractions. These fractions were also subjected to attracting experiments in water tank to estimate attracting effects. The aqueous fractions of mackerel and tuna viscera showed the highest attraction effect on swimming crab. The major chemical compounds of the aqueous fractions were histidine, taurine, cysteine, glutamic acid, inosine monophosphate (IMP) and inosine (HxR) for mackerel and arginine, glutamic acid, aspartic aid, alanine, IMP and hypoxanthin (Hx). Results indicated that higher polarity compounds, such as amino acid and nucleotide related compounds have higher attraction activities than nonpolar substances such as neutral lipid.