Crustacean hyperglycemic hormone (CHH), a polypeptide with multiple physiological effects, was first identified in the X-organ/sinus gland neurosecretory system of the eyestalks. In studies reported here, we used a PCR-based cloning strategy (RT-PCR followed by 5′- and 3′-RACE) to clone from blue crab (Callinectes sapidus) eyestalk ganglia a cDNA (CsCHH-1) encoding a putative CHH preprohormone. Sequence analysis revealed the preprohormone included all structural features previously reported for CHH preprohormones: a signal peptide, a CHH precursor-related peptide (CPRP), the CHH polypeptide, and a C-terminal basic processing site. Further, the deduced amino acid sequence of the mature polypeptide included all signature domains previously reported for CHH. The primary structure of blue crab CHH is most closely related to CHH from other brachyurans. RT-PCR revealed the CsCHH-1 transcript was present in eyestalk ganglia, but was undetectable in other tissues tested. A transcript encoding a similar CHH-like preprohormone was detected in thoracic ganglion, ventral nerve cord, and brain, but was not detected in eyestalk ganglia. © 2006 Elsevier Inc. All rights reserved.