A biochemical analysis was made of the crustacean hyperglycemic hormone (CHH) of the crayfish Astacus leptodactylus, as present in the CHH-producing perikarya, in the axonal tract and in the sinus gland, respectively. Hyperglycemic material was analyzed by polyacrylamide gel electrophoresis (PAGE and SDS-PAGE) and high-pressure liquid chromatography (HPLC) in combination with a dotting immunobinding assay (DIA) and a bioassay for hyperglycemic activity. After electrophoretic analyses, the predominant biologically as well as immunologically detectable product present in all parts of the cell has an apparent molecular radius of approximately 7000 Da. In the perikarya extract, a second factor with lower electrophoretic mobility was found, which may represent the prohormone or precursor of CHH. The analyses by means of HPLC showed two predominant immunopositive peaks with an elution time of 28-29 and 52-54 min, respectively. For both HPLC peaks, electrophoretic analyses indicate a molecular weight of 7000 Da.