Social studies in science have paid particular attention to scientific controversies; but not necessarily in relation to the role of the media, which is often analysed as a matter of public communication of science. In this work, however, the two dimensions are linked, analysing the role of mass media in the debate that focused on chrotoxin as a potential cancer cure, which was at the centre of the public sand in mid-1986 in Argentina. The case was reconstructed from the analysis of the newspapers and television programmes of the time, through interviews with the central actors involved in the conflict and through secondary sources. By analysing how a particular scientific situation comes to dominate the public arena, this work seeks to contribute to the understanding of a phenomenon of growing relevance in today’s societies: how mass media have an impact on science-based controversies by putting a certain way of understanding a scientific topic on the public agenda.