In this book, DNA- based cryptography methods are proposed as combined with data hiding techniques for an increased level of security using basic concepts and properties of the Deoxyribonucleic Acid (DNA). These methods are implemented mainly on two stages: the first encrypts the plaintext using Amino acid and DNA based Playfair cipher. The second applies a secure insertion, complementary or substitution methods to hide the encrypted DNA ciphertext into some reference DNA sequence. The proposed techniques are Playfair-insertion, Playfair-complementary and Playfair-substitution. Finally, Playfair-insertion-substitution method is introduced to achieve extremely data security.