BackgroundPatients’ perception of receiving overtreatment can cause distrust in medical services. Unlike outpatients, inpatients are highly likely to receive many medical services without fully understanding their medical situation. This information asymmetry could prompt inpatients to perceive treatment as excessive. This study tested the hypothesis that there are systematic patterns in inpatients’ perceptions of overtreatment.MethodsWe examined determinant factors of inpatients’ perception of overtreatment in a cross-sectional design that used data from the 2017 Korean Health Panel (KHP), a nationally representative survey. For sensitivity analysis, the concept of overtreatment was analyzed by dividing it into a broad meaning (any overtreatment) and a narrow meaning (strict overtreatment). We performed chi-square for descriptive statistics, and multivariate logistic regression with sampling weights employing Andersen’s behavioral model.ResultsThere were 1,742 inpatients from the KHP data set that were included in the analysis. Among them, 347 (19.9%) reported any overtreatment and 77 (4.42%) reported strict overtreatment. Furthermore, we found that the inpatient’s perception of overtreatment was associated with gender, marital status, income level, chronic disease, subjective health status, health recovery, and general tertiary hospital.ConclusionMedical institutions should understand factors that contribute to inpatients’ perception of overtreatment to mitigate patients’ complaints due to information asymmetry. Moreover, based on the result of this study, government agencies, such as the Health Insurance Review and Assessment Service, should create policy-based controls and evaluate overtreatment behavior of the medical providers and intervene in the miscommunication between patients and providers.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12913-023-09563-9.