ENMaritime/marine spatial planning (MSP) is a general term that designates integrated sea governance through balancing the demands of development and the need to protect the environment. By applying the ecosystem-based approach, MSP is the most commonly accepted management framework for promoting the long-term sustainability and Blue Growth of the marine environment globally. Among the MSP process’s several main phases, the implementation phase can lead to revision, adapting the MSP process. This paper analyses implementation, i.e., performance of maritime spatial plans (maritime or marine plans, used interchangeably) in the three Baltic Sea basin countries, i.e., Estonia, Latvia, and Lithuania, considering the status quo of the MSP in each country. In 2014, Directive 2014/89/EU of the European Parliament and of the Council establishing a framework for MSP (the MSP Directive) was adopted. Following two pilot marine plans (the area around Hiiu Island and Pärnu Bay area), currently in Estonia the initial outline for the maritime plan is being prepared, with additional public display of the draft. In turn, in Latvia, on 14 May 2019, the Government approved the maritime plan until 2030. In Lithuania, the marine plan was prepared in 2014 and adopted by the Parliament in 2015.In this study, evaluating implementation of performance of the maritime plans is proposed by 1) examining the principles used in national MSP, 2) exploring the influence of existing regulation and soft law tools on an international, national, regional and local level, 3) taking into account compliance with the minimum requirements set out by the MSP Directive, 4) clarifying opportunities and threats resulting from adoption of maritime plans, 5) exploring best practice examples. Key Words: maritime/marine spatial planning, adaptive management, monitoring, performance evaluation, Baltic States.