[Arg7]- corazonin is a neuropeptide produced in the pars lateralis of the brain. It is stored in the corpora- cardiaca and released from there into the heamolymph. Corazonin first isolated from corpora-cardiacum (CC) of Periplaneta americana as the most potent cardiostimulatory peptide was recently reported to have no effect on the physiological regulation of cardiac functions in the living body of American cockroach (Slama. K et al, 2006). Till date the only well documented effect of this neuropeptide in locust is increased melanization of the cuticle. We investigated and confirmed the presence of this neuropeptide in a limited number of neuroseceratory cells of different brain region of last instar nymph and adult german cockroach through Immunohistochemistry. We found distinct difference in the cell morphology and peptide expression during these important phases of the cockroach. We also checked whether this neuropeptide might be casually related to changes in behavior and morphometrics that, melanization pattern of newly ecdysed albino nymphs and adult Blatella germanica. Our results indicate that [Arg7]- corazonin is not involved in any morphometric changes but confirms to play significant role in the increased melanization of both developmental stages of the cockroach species.