A number of various techniques have been already developed for providing security in sensor networks. It may be anticipated that these techniques provide less secure sensor network which has numerous adverse effects associated with them. Thus there is a sufficient scope for improvement of secure electronic communication, as the proficiency of attacks is growing rapidly in wireless sensor networks. DNA steganography is a technique of covered writing, which provides secure system in sensor network to some extent. Steganography is more effective over cryptography as later one only conceals information but steganography obscures the information, as well as camouflage the data to various attackers. DNA steganography is an inventive approach to reduce the popularity of public key cryptography over the wireless sensor networks. In the proposed work, a secret key is introduced which is purely based on DNA sequence named as DNA stego key and is only known to sender and receiver. This D