Abstract Background Commercial entities are increasingly interested in acquiring Dutch general practices (GPs). They see profitable opportunities in upscaling by forming chains. Chain organizations integrate business processes of GPs within one organizational unit. The governance structure of these chains can be complex, leading to opacity and difficulties to see conflicts of interest and market power. To investigate how this development may have an impact on quality and accessibility of care, it is first needed to establish the ways in which these chains are formed. By mapping the chain structure in a data-driven way, impact monitoring becomes possible. For the Netherlands we investigated how chain structures of GPs can be empirically identified. Methods Background data of approximately 4,800 Dutch GPs from the Nivel Healthcare Professional Registries was linked with data from the Chamber of Commerce’s Trade Register. This enabled the determination of the legal form, business location, ownership, and director identification for all GPs. By this data-driven manner, the variation in organizational structures of all Dutch GPs was mapped and analyzed. Results Four different chain variants of Dutch GP chains were identified based on three types of relations between the chain organization and their GPs: ownership, location and the composition of the board of directors. Based on ownership, two ‘top-down’ chain variants were identified. Two ‘bottom-up’ chain variants were found based on location and board composition: (1) a chain organization acquires a seat on the board of the GP, and (2) the GP and the chain organization share the same business address. Combining these variants provides a new typology of GP chains in the Netherlands. Conclusions Our methodology enables to empirically map chain formation in primary care. By developing a new typology in a systematic way, a foundation is created to monitor organizational developments and their impact on quality and accessibility of care. Key messages • A typology of Dutch GP chains was developed based on three relations: the ownership, composition of the board and the establishment location of the chain organization and its practices. • Our methodology was put into practice to map different chain structures of GPs in the Netherlands, but it is not limited to primary care and can also be applied in other sectors and countries.