Abstract: The work is devoted to the urgent problem of ensuring the security of heterogeneous information platforms, using the system of electronic support of on-line communications processes in a medical institution - e-health online communications. The authors pay special attention to such important aspects of the topic as: the security of heterogeneous information platforms, the model for the protection of heterogeneous information platforms, the classification of communications and the protection mechanisms of MMK. The tendencies for the development of new distributed safety models are considered. This article presents a model of multi-level communications. A classification of communications and protection mechanisms for each level with different security levels using cryptography protocols is proposed. Security flexibility can be provided to health organizations using a variety of key size combinations to protect data and channels. At each level, different levels of security can be provided depending on the sensitivity of the data. Thus, we came to the MMK model as a solution to the problem of communication in e-health and other large organizations with a distributed network of computer communications.