The subject of the study is the conceptual, legislative and theoretical provisions in the field of legal regulation of contractual relations in the implementation of joint activities in Ukraine and some European countries, as well as in the field of using the structure of joint activities as a special type of economic relations in the conduct of business. Methodology. General scientific methods were used in the research process. The comparative method was used to compare the legislative approaches to the legal regulation of contractual relations in the joint activities of Germany, France, Poland, Moldova and Ukraine. The analysis was used to determine the specifics of legislative approaches to the legal regulation of contractual relations for the implementation of joint activities in these countries, to identify their advantages and disadvantages. Synthesis was used to determine the methodological principles of legal regulation of joint activities. Induction and deduction were used to determine the basic principles of the functioning of civil legal partnerships with the aim of carrying out joint activities by their participants. The aim of the article is to propose concrete ways of improving the Ukrainian legal mechanism of contractual regulation of joint activity relations in order to ensure prompt and efficient post-war reconstruction of destroyed infrastructure facilities, the success of the process of recodification of the civil legislation of Ukraine and its harmonisation with the legislation of the EU countries. The results of the study have shown that, in general, the Ukrainian legislative approach to the legal regulation of relations on the implementation of joint activities is the most liberal and dispositive in comparison with the corresponding approaches of the European countries, which confirms the opinion that it is necessary to understand the agreement on joint activities as an effective legal and economic instrument for the post-war reconstruction of Ukraine, based on the consolidation of human efforts and resources (capital) for the achievement of a common goal. Conclusion. In order to improve the national legislative approach to the legal regulation of relations on joint activities on a contractual basis and to harmonise it with the provisions of European legislation, it is advisable to enshrine the following provisions by way of borrowing: 1) the prohibition of participants to engage in any activity that may be detrimental to the company, including the prohibition of competition; 2) the possibility of depriving a participant of the right to manage the company by a court decision if there is a valid reason, in particular as a result of a gross breach of duty; 3) the right of a participant to withdraw from a limited partnership if there are valid reasons and the invalidity of the objection to this effect; 4) the establishment of a basic list of the essential terms of a simple partnership agreement. This will undoubtedly have a direct impact on improving the institution of joint ventures as an important tool for the development of Ukraine's economic system in the post-war environment, especially in the context of investing in Ukrainian business and rebuilding the destroyed infrastructure.