The chemical components, lipid class, and fatty acid composition of the viscera from male and female common squid, Todarodes pacificus, were examined to evaluate the possible utilization of the liver, reproductive organs, and gills. In male and female squid, the viscera comprise 21% and 27% of the body weight, respectively. The protein content of the viscera was slightly higher in females (17.7-19.5%) than in males (15.6-17.2%). This was especially marked in the female reproductive organs, while there was little difference in the gill. The liver contained the largest amounts of lipids (17.2-18.6%) and the levels were higher in males than in females (P<0.01). By contrast, the reproductive organs of females contained more lipids than did those of males (4.68% vs. 1.65%, p<0.01). The prominent non-polar lipid (NL) classes were triacylglycerol (51.9-55.4% of the NL content) and sterol ester (16.3-21.8%) in the liver, and free sterol (47.0-68.5%) and free fatty acids (31.5-41.2%) in the reproductive organs. However, there were no significant differences in the NL classes between sexes. The percentage of the most prominent phospholipid (PL) class, phosphatidylcholine (PC), was highest in the liver (78.1-79.6% of the PL content), and there was no significant difference between the sexes. By contrast, phosphatidylethanolamine (PE) was highest in the reproductive organs (33.4%), and was higher in males than in females (P<0.05). All the visceral organs contained 36.4-48.5% of n-3 polyunsaturated fatty acids (PUFA), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The DHA level was highest in female reproductive organs (32.3%), while EPA was high in male reproductive organs. These results demonstrate that the viscera of male and female common squid are a good source of DHA and EPA.