The works presented in this paper show how encryption algorithms provide security to medical imagery. The main objective is to guarantee the protection of medical images during transmission, and also once this digital data is archived. The subsequent challenge is to ensure that such coding withstands severe treatment such as compression. For ethical reasons, medical imagery cannot be sent when such a risk is present, and has to be better protected. Encryption is the best form of protection in cases such as this. Many different techniques for the encryption of text already exist. In this paper we show how essential it is to ensure the security of medical imagery and data.