Through users’ cross-system comparative experience engaging with the health systems in Taiwan and other countries, this article probes into their understandings and value judgments and specifically their reasonings for the ‘solidarity with whom?’ question in the health sector solidarity. With the cross-system comparison approach, the study adopted semi-structured interviews with 30 Taiwanese participants who have studied, lived or worked abroad and engaged with the health system in Canada, the USA or the UK. This approach offers the opportunity for one to (...) evaluate the health system in the home country from a relative viewpoint from the host country. The participants suggested that the boundary of Taiwan’s National Health Insurance (NHI) should be as inclusive as possible, covering all legal residents in Taiwan regardless of their status, and that the citizens should share more financial responsibility. The ethical reasons for supporting the NHI include recognizing health sector solidarity among people, considering the coverage as a protection of the human right to health, humanitarian reasons and self-interest. Three archetypes of users emerged from the synthesis: Universalists, Rationalists and Republicans. The cross-system comparative experience makes the participants have more supportive attitudes toward the ideals of health sector solidarity. (shrink)