This study was attempted to establish the basic data for evaluating taste compounds in fermented entrails of Clupanodon Osdeckii. The changes of such compounds as amino acids, nucleotides and their related compounds, betaine, TMAO and TMA during fermentation were analyzed. IMP, AMP, ADP and ATP were decreased, while hypoxanthine was increased during the fermentation. The content of hypoxanthine in fermented entrails of Clupanodon Osdeckii after 50 days was increased to about 2 times of that in raw entrails. In the free amino acid composition of raw entrails, abundant amino acids were lysine, glutamic acid, valine, alanine, threonine, serine, leucine and glycine in order. Such amino acids as arginine, tyrosine and phenylalanine were lower than 2.0% of total free amino acid, and proline and cysteine were detected in trace amount. The changes in free amino acid composition of the extract in entrails of Clupanodon Osdeckii during fermentation were not observed. Such amino acids as lysine, glutamic acid, valine, serine and leucine were especially abundant in both raw and fermented products. The content of total free amino acids in fermented entrails of Clupanodon Osdeckii after 50 days were increased to about 12 times of that in raw. The content of betaine nitrogen were about 14.5 (moisture and salt free base) after 50 days of fermentation. TMAO nitrogen was decreased during the fermentation. It is believed that lysine, glutamic acid, valine, serine, leucine and hypoxanthine play an important role as taste compounds in fermented entrails of Clupanodon Oseckii.