The growing competitiveness and growth of the tourism industry have put tourism beneficiaries on the path of thinking and appropriate strategic and futuristic action to enhance the destination's competitiveness. Therefore, this study aims to analyze the impact of organizational capacity development components on the competitiveness of Sarein spa tourism destinations and, consequently, the research model is quantitative. The required initial data were collected based on a questionnaire tool and from a sample population of over 200 people in two chain methods (for experts of organizations and related services) and random (for tourists) in Sarein city. Findings indicated that from organizational capacity development, the components of leadership capacity, human resources and especially communication are weak. Also, from the viewpoint of competitiveness, apart from the appropriate conditions of the resource quality component, the other two components, namely destination management and the competitive performance component, are not suitable for promoting tourism development. Structural equation modelling demonstrated that the components of organizational capacity development have a positive and significant effect on the competitiveness of Sarein spa tourist destinations. Proving this effect can provide a new thematic context for the development of related literature to improve the competitiveness of the destination.IntroductionThe focus and purpose of the research is to analyze the impact of organizational capacity development components on the competitiveness of the spa tourism destination in Sarein. "Organizational capacity development" as an intermediate and important link of capacity system components (individual, organizational and systemic), organized application of leadership and management, organizational resources and culture and communication processes to improve the capabilities and functions of the organization over time and in a way which is considered stable (UNDP,2009; Aref,2011).  Alongside the changes in travel patterns over the past few years, the new trends indicated the strengthening of the spa and medical tourism product (Csapó & Marton; 2017; 56) which, due to the growth of the global health tourism market, has made it necessary to be competitive in this field.The competitiveness of tourist destinations is one of the most important factors in the success of the destination (Paunovi'c et al., 2020). The argument is that competing tourist destinations seek to satisfy tourists and expand their share of the target market (Cronje & Plessis, 2020). In this regard, competitiveness can be considered the ability of the destination to optimize attractions (products and services) and sustainably create added value to maintain a competitive position of the destination and provide suitable conditions for the unique experience of visitors and better quality of residents' lives and care for local capital (natural and heritage) over time (Fernández et al., 2020).Materials and research methods The present study is based on quantitative research regarding applied purpose and research pattern. Based on the available literature, the conceptual research model is organized in the form of independent (organizational capacity development) and dependent (destination competitiveness) variables. The conceptual components of the proposed model in the field of organizational capacity development, leadership capacity (management), organizational capacity, resource capacity and communication have been determined. In destination competitiveness, three key components of resource and product quality, destination management and marketing factors, and Competitive destination performance are defined. Based on the available literature, 14 components and 80 variables have been used to design the questionnaire tool to implement the above concepts. Preliminary data were collected through surveying in the target statistical population and based on 200 sample populations of experts from executive organizations and activists of industry and related services in Sarein, and relationships were tested based on structural equation modelling (in Smart PLS software environment). The scale of the questionnaire items was the Likert five-choice range.Findings and discussionBased on descriptive findings, the average response rank of organizational capacity development items and destination competitiveness in Sarein city is lower than the average of 3 (from the fifth rank ceiling). It indicates a gap in the capacity of organizations for destination development and competitiveness. Based on the findings and within the framework of organizational capacity, the status of the human resources component had the best, and organizational communication had the worst mean response rank.ConclusionStructural equation modelling indicated that the designed structure and the causal relationships fit properly. As a result, the coefficients of the items and the path pattern of the relationships are significant. In other words, this hypothesis confirmed that the development of organizational capacity has a positive and significant effect on the competitiveness of the spa tourism destination in Sarein.