Abstract DNA-based molecular testing for human papillomavirus has emerged as a novel approach to cervical cancer screening in the context of well-entrenched existing technology, the Pap smear. This article seeks to elucidate the process of molecularisation in the context of screening programmes. We illustrate how, although Pap has long been problematised and could be seen as a competing technological option, the existing networks and regime for Pap were important in supporting the entrenchment process for the artefacts, techniques and new diagnostics industry entrant, Digene, associated with the new test. The article provides insights into how the molecularisation of screening unfolds in a mainstream market. We reveal an incremental and accretive, rather than revolutionary, process led by new commercial interests in an era when diagnostic innovation is increasingly privatised. We show Digene�s reliance on patents, an international scientific network and their position as an obligatory point of passage in the clinical research field with regard to the new technology�s role, as well as on controversial new marketing practices. The article is based on a mixed method approach, drawing on a wide range of contemporary sources (including patents, statutory filings by companies, scientific literature and news sources) as well as interviews.