Background and Purpose: Considering the numerous concerns patients express about having implantable cardioverter-defibrillators (ICDs) and the potential clinical implications of these concerns, it is essential to develop a valid and reliable measure of ICD-related concerns. The implantable cardioverter-defibrillator concerns (ICDC) questionnaire was initially designed for ICD recipients in England to assess and address these concerns. However, it remains uncertain whether this questionnaire possesses similar measurement properties and is suitable for ICD recipients in the United States. The purpose of this study was to provide evidence of the reliability and validity of the ICDC among ICD recipients in the United States with the aim to evaluate the internal consistency reliability of the ICDC, provide evidence of construct validity using Exploratory Factor Analysis (EFA), and test the hypothesis that higher scores on the ICDC would predict higher anxiety levels as measured by the Brief Symptoms Inventory-Anxiety (BSI-6). Methods: Data from a cross-sectional observational study of 240 adult ICD recipients were used to test their knowledge, attitudes, and perceptions of ICDs. Cronbach's coefficient α (alpha) was calculated to assess reliability. EFA using principal components analysis was conducted to evaluate validity. Results: Cronbach's coefficient α (alpha) was .94, indicating high reliability. The results of the EFA suggested that a one-component solution was optimal. The correlation between the BSI-6 measure of anxiety and the ICDC total score was positive and statistically significant. Conclusions: The findings from this study support the reliability and validity of the ICDC questionnaire among ICD recipients in the United States.