Background Hospitals are increasingly parts of larger care collaborations, rather than individual entities. Organizing and operating these collaborations is challenging; a significant number do not succeed, as it is difficult to align the goals of the partners. However, little research has focused on stakeholders’ views regarding hospital collaboration models or on whether these views are aligned with those of hospital management. This study explores Belgian hospital stakeholders’ views on the factors affecting hospital collaborations and their perspectives on different models for Belgian interhospital collaboration. Methods Qualitative focus group study on the viewpoints, barriers, and facilitators associated with hospital collaboration models (health system, network, joint venture). Results A total of 55 hospital stakeholders (hospital managers, chairs of medical councils, chair of hospital boards and special interest groups) participated in seven focus group sessions. Collaboration in health care is challenging, as the goals of the different stakeholder groups are partly parallel but also sometimes conflicting. Hospital managers and special interest groups favored health systems as the most integrated form. Hospital board members also opted for this model, but believed a coordinated network to be the most pragmatic and feasible model at the moment. Members of physicians’ organizations preferred the joint venture, as it creates more flexibility for physicians. Successful collaboration requires trust and commitment. Legislation must provide a supporting framework and governance models. Conclusions Involvement of all stakeholder groups in the process of decision-making within the collaboration is perceived as a necessity, which confirms the importance of the stakeholders’ theory. The health system is the collaboration structure best suited to enhancing task distribution and improving patient quality. However, the existence of networks and joint ventures is considered necessary in the process of transformation towards more solid hospital collaborations such as health systems. Electronic supplementary material The online version of this article (10.1186/s12913-018-3763-9) contains supplementary material, which is available to authorized users.