Abstract In market-based healthcare systems, due to the high and increasing degree of integration between healthcare providers and purchasers, the enforcement of the cartel prohibition is both important and ever more complex. Competition authorities operate independently, but their approach to enforcement may be influenced by the public and political context. Within the setting of the Dutch healthcare system, we study how the cartel prohibition was enforced between 2004 and 2020 and focus on whether a relationship with public and political attitudes towards competition in healthcare can be observed. Using both qualitative and sentiment analyses, we assessed 38 formal and informal documents issued by the competition authority, 126 written parliamentary questions and almost 1,500 newspaper articles. Our findings reveal that during the first half of the study period (2004–2012), ex-post punitive formal enforcement of violations of the cartel prohibition, such as market-sharing and price-fixing agreements, predominated. During the second half of the study period (2012–2020); however, the competition authority’s focus seems to have shifted toward providing ex-ante informal guidance. We clearly observe negative public and political attitudes towards competition in healthcare as well as a distinct shift in enforcement of the cartel prohibition in Dutch health care. However, we are not able to test for a causal relationship between both observations.