By ion-exhange column chromatography, the tryptophan metabolites have been, determined in eggs, at different time of incubation, of a pigmented strain and an albino strain of Schistocerca gregaria (Orthoptera). In both strains kynurenine was found in freshly laid eggs and in later stages until hatching. From the 10th days of incubation 3-hydroxykynurenine was present, increased notably at the hatching (the 14th day) in the pigmented strain and in a lesser extent in the albino animals. Kynurenic and xanthurenic acids appeared in small amounts at the end of embryonic development; no other tryptophan metabolite seemed to occur. The results were discussed in relation to the ommochrome synthesis..