Interest in alternative organizations and their emancipatory potential has grown significantly among critical scholars. Among current inquiries, it has been shown that these organizations may be " contaminated " (i.e.: implement anti-alternative practices and/or adopt capitalist values) when competing, on their markets, with traditional capitalist organizations. But what happens when alternative organizations compete with one another or operate in a market that consists exclusively of other alternative organizations? Does their alternative nature help them deal differently with the competition-related issues they face, to develop solutions and practices other than those they would implement if they were competing with privately-owned capitalist enterprises? In this research, we have explored a sector – that of student healthcare in France – that involves two alternative, mutualist organizations competing directly and exclusively with each other. Focusing on the relations of competition between these mutuals, we observed in the field that their practices and methods greatly contrasts with the mutualist values and principles those organizations claim to stand for, in particular with the principles of solidarity between members and of non-commercialization of health care. This case shows how the alternative nature of an organization becomes diluted in the issues of competition even though the market is shared by two alternative non-profit organizations. We suggest that the situation of direct competition by itself, and not only competition with traditional capitalist organizations, is a key determinant of alternative organizations' ability to put into practice their distinguishing principles.