The study was conducted on the basis of the contradictory nature of Ukraine's cooperation with the North Atlantic Treaty Organization, established in 1992. On the onehand, Ukraine has consistently stated its intention to integrate into NATO as a full member. The country has formed an organizational and legal mechanism for cooperation with NATO. The reis an indefinite Charter on a Distinctive Partnership between Ukraine and NATO. Intentions for full membership in the Alliance are included in the Constitution of Ukraine and national security legislation. The norm of cooperation between the parties is the development and signing of various programs for cooperation in security, defense, education and other areas. The majority of Ukrainian society supports the state's intention to join NATO. On the other hand, despite long-term cooperation with the Alliance, Ukraine has not receivedan Action Plan for NATO membership, which makes the ultimate goal of integration unattainable. The main obstacle to Ukraine's Euro-Atlantic integration has been and remains the insufficient pace of reforming the country's political, economic, judicial and other basic systems, as well as the security and defense sector. The over all result of the study is to emphasize the attention of the Ukrainian side to the need to accelerateur gent state reforms, update the existing organizational and legal mechanism of cooperation between Ukraine and NATO, bringing all components of the security and defense sector to Western standards. The conclusions point to the main contradiction in the practical support of Ukraine's Euro-Atlantic movement: the national state-building elite did not ensure the continuity of the political course on Euro-Atlantic integration and the accumulation of constructivism along the way. The hypothesis of the study was to prove the existence of a "medium" level of cooperation between Ukraine and NATO on the basis of the existing organizational and legal mechanism, which does not yetallow to raise the issue of Ukrainian integration into the Allianceon a full basis.The hypothesis is generally proven. It is considered appropriate to further monitor the state, problems of functioning, prospects for the development of the organizational and legal mechanism of Ukraine's cooperation with NATO with the formulation of appropriate recommendations to improveits effectiveness.