A considerable amount of spending in health care is deemed wasteful. Overdiagnosis, i.e. the labelling of a person with a diagnosis that lacks net benefit, is an entity within the overarching concept of »too much medicine«. Overdiagnosis includes overdetection and overdefinition. Disease mongering is a type of overdefinition with economic drivers. Overtesting and overtreatment are other aspects of »too much medicine«, but are not overdiagnosis per se. Medical research tends to focus on benefits of diagnostics and therapy, whereas overdiagnosis and other harms receive less attention, leading to overestimation of benefits. The international network Choosing Wisely has been successful in changing the diagnostic mindset in several countries and a Swedish campaign is under way, yielding new possibilities to counteract »too much medicine« and the specific problem of overdiagnosis.