Background and Purpose:High-alert medication is considered to be a medication that presents a high risk of causing significant patient harm when used erroneously and its consequences can be fatal. The Nurses' Knowledge of High-Alert Medication scale (NKHAM) is a tool available to evaluate the knowledge of nurses in practice about this issue.Aim:This pilot study aimed to measure the reliability and known-groups validity of the Brazilian version of the NKHAM.Methods:This pilot psychometric study was carried out at the Faculty of Nursing and University Hospital of the University of Campinas, São Paulo, Brazil. Forty nursing students and 44 registered nurses working in complex clinical or surgical settings completed a sociodemographic questionnaire and the Brazilian version of the NKHAM. The Kuder–Richardson 20 (KR-20) coefficient and Mann–Whitney test were used to establish reliability and known-groups validity. A significance level of ≤ 0.05 was adopted for all the analyses.Results:Analyses demonstrated preliminary acceptable reliability scores of 0.55 and 0.60 in domains A and B of NKHAM, respectively. A significant difference was found between the nursing students' and the registered nurses' knowledge of high-alert medications, demonstrating the scale's ability to discriminate between the two groups.Implications for Practice:Although this is pilot study, results suggest that the Brazilian version of the NKHAM might be a reliable and valid tool to measure nurses' knowledge of high-alert medications.