Problem setting. Problems of international relations and foreign policy have always been in the center of public attention of analysts, politicians and journalists. Although secret diplomacy is a highly controversial phenomenon in terms of public morality, it is an effective means of pursuing defense policy, military cooperation and establishing international relations for peace. In practice, secret diplomacy has various forms of implementation, such as holding “closed” conferences, signing secret multilateral agreements, providing covert instructions, and others. Any form of implementation must take into account the fact that the ultimate goal is to achieve the maximum national interest with a minimum of controversy and resentment from others. Analysis of recent researches and publications. Among Ukrainian scholars, D. Kostyuk and D. Kurillo, S. Pik and others. Anthony John Wanis-ST., a professor of the American University’s School of International Service in Washington, D.C., made a significant contribution to the study of secret diplomacy. John, Cornelius Biola, a professor at Oxford University, and Aaron Klieman, a professor at Tel Aviv University. Target of research is to define the concept of secret diplomacy, analyze the main ways of its implementation, as well as explore the features of their functioning in international relations. Article’s main body. The research is devoted to the definition of “secret diplomacy” and analysis of the main ways of its implementation. Peculiarities of the functioning of forms of secret diplomacy in international relations have been studied. Forms of secret diplomacy include “closed” conferences, secret bilateral and tripartite agreements, the provision of secret instructions by states to diplomats, correspondence through closed channels, and non-public diplomacy. The definition of “secret diplomacy” is proposed. Examples of the application of secret diplomacy in practice have been studied. “Secret” conferences are a very effective way to reach agreement on some common issues, they are difficult because of both the organization and the stage: the more participants in the negotiations, the more difficult it is to maintain secrecy and control information leaks. Details of such negotiations are often leaked to the media, causing serious harm to participants. The signing of secret bilateral and tripartite agreements allows countries to significantly expand the range of issues under discussion, including all issues, from cooperation in various sectors of the economy, military cooperation to joint action in the international arena. The practice of giving secret instructions to diplomats is often used: when sending a diplomatic mission, the state provides its members with a number of mandatory secret instructions, as well as coordinates its work during negotiations. Closed channel correspondence, the biggest advantage of which is the small number of people who take part in it, which in turn allows the sender and recipient to keep all correspondence secret, preventing the essence of correspondence from being revealed to third parties. Non-public diplomacy consists of negotiations officially authorized by the leadership of states, which take place between the parties to the conflict in secret from other parties. Conclusions and prospects for the development. Despite the disadvantages, covert diplomacy can create an enabling environment for constructive negotiations by isolating foreign policy figures from public speaking, giving them the highest level of security, informality, autonomy and the ability to “save face” in public. It is not a universal way to solve all problems, but, in our opinion, it is an effective method of resolving protracted conflicts that negatively affect world politics.