A porgy was divided into eight parts. After drying at low temperature and pulberizing it, the sample was hydrolyzed by $Ba(OH)_2{cdot}8H_2O;at;120^{circ}C$, under the pressure of $1;kg/cm^2$ for 8 hours. Tryptophan was determined by means of microbiological assay, using Lactoba-cillus arabinosus 17-5. The result of experiments was as follows: The content of nitrogen of eight parts of the body amounted $12.55\%$ in muscle being the highest of all, $11.49\%$ in heart, $11.31\%$ in eyeball, $11.22\%$ in liver, $11.06\%$ in intestine, $8.75\%$ in head, $7.81\%$ in gill, and $6.02\%$ in fin which was the lowest of the parts tested. The content of tryptophan per 1 gram nitrogen was 11.79mg in liver, which was the highest of all, 10.11mg in heart, 9.76mg in eyeball, 8.77mg in intestine, 6.28mg in muscle, 5.72mg in head, 4.03mg in gill 2.64mg in fin, and in that order.