Medication errors are common in hospitals. These errors can result in adverse drug events (ADEs), which can reduce the health and well-being of patients', and their relatives and caregivers. Interventions have been developed to reduce medication errors, including those that occur at the administration stage. Objective We aimed to elicit willingness-to-pay (WTP) values to prevent hospital medication administration errors. Design and setting An online, contingent valuation (CV) survey was conducted, using the random card-sort elicitation method, to elicit WTP to prevent medication errors. Participants A representative sample of the UK public. Methods Seven medication error scenarios, varying in the potential for harm and the severity of harm, were valued. Scenarios were developed with input from: clinical experts, focus groups with members of the public and piloting. Mean and median WTP values were calculated, excluding protest responses or those that failed a logic test. A two-part model (logit, generalised linear model) regression analysis was conducted to explore predictive characteristics of WTP. Results Responses were collected from 1001 individuals. The proportion of respondents willing to pay to prevent a medication error increased as the severity of the ADE increased and was highest for scenarios that described actual harm occurring. Mean WTP across the scenarios ranged from 45 pound (95% CI 36 pound to 54) pound to 278 pound (95% CI 200 pound to 355) pound. Several factors influenced both the value and likelihood of WTP, such as: income, known experience of medication errors, sex, field of work, marriage status, education level and employment status. Predictors of WTP were not, however, consistent across scenarios. Conclusions This CV study highlights how the UK public value preventing medication errors. The findings from this study could be used to carry out a cost-benefit analysis which could inform implementation decisions on the use of technology to reduce medication administration errors in UK hospitals.