Background Higher patient-caregiver mutuality is associated with improved patient and caregiver outcomes, but no studies have tested the psychometric characteristics of the mutuality scale (MS) in heart failure (HF) patient and caregiver population. Objectives To test the validity and reliability of the MS. Methods A cross-sectional design. The MS validity and reliability were tested with confirmatory factor analysis (CFA) and hypothesis testing, and with Cronbach's alpha and model-based internal consistency index, respectively.