The process of sending data through the Internet is vulnerable to tampering and theft, so protection has become a necessity. Many solutions have proposed to solve this problem in order to protect the sending data and conceal them in a way that cannot be penetrated or proven by nature. The paper proposes a method to hide data in a Deoxyribonucleic acid (DNA) using Postfix conversion according to the embedded bits. The method has proved its security in concealing the information, not predicting its nature, and preserving the biological structure of the DNA sequence