DNA computing is the back bone of the DNA cryptography. DNA cryptography is becoming an alternative to the traditional cryptographic approach that exists in our day-today life. In spite security breaches overwhelm the traditional security techniques that are provided to a system. Thus, to increase the security feature with less cost and reduced computational time, we go for techniques utilizing the properties of DNA molecules. The various properties and methods that adopt DNA cryptography to provide security to the messages transmitted between a sender and a receiver are explored. This paper discusses about schemes of DNA cryptosystems proposed by various researchers.