Medical overuse is defined as health care services that exceed the individual needs of patients and when the potential harms of medical interventions exceed their benefits. It has impacts on patients as well as on health care resources. To address medical overuse, it is important to understand the knowledge and experiences of overuse on the side of patients. What is the citizens' understanding of overuse? How do they assess its relevance, causes, consequences and potential solutions? A quantitative online survey was conducted. The participants were asked to state what they understand by medical overuse. Statements on causes, consequences and possible solutions were evaluated. Recruitment was carried out via a panel of a market research institute (Schlesinger Group). The survey was completed by 406 participants. In terms of age and gender, the sample corresponded to the distribution in the German population. The majority had never heard of medical overuse (58%). About 60% assumed that medical overuse means "too much medicine including overtreatment and overtesting". Medical overuse was mainly suspected for services not covered by the public health insurance system (56%), surgical interventions (45%) and medication prescriptions (37%). Reasons for medical overuse were seen in uncoordinated care and financial incentives, but also in the expectations of patients. The main problem with medical overuse was seen in rising health care costs, while harmful physical and mental consequences for patients were mentioned less often. In order to reduce medical overuse, little importance was attributed to a primary care based system or higher financial contribution of patients. Instead, stricter cost control on the side of physicians and better coordination between care providers were suggested as solutions. Differences in socio-demographic characteristics hardly showed any differences in response behavior. More than half of the respondents had never heard of medical overuse. Overuse was mainly associated with financial causes and consequences. It was not seen that overuse can be harmful for patients directly. The limited awareness of the problem of overuse probably is a barrier to tackling it effectively. Communicating the topic to the public might therefore be an effective start to mitigate medical overuse. Many citizens seem not to be familiar with the concept of medical overuse, especially not with the fact that it may directly cause harm to patients. Informing citizens about the harms of medical overuse might be helpful in mitigating it.