Background and Purpose: Family caregivers of heart failure (HF) patients describe feelings of uncertainty; however, studies measuring uncertainty in caregivers of HF patients are extremely sparse. This study examined the validity and reliability of the Mishel Uncertainty in Illness Scale-Family Member form (PPUS-FM) in caregivers of HF patients. Methods: Caregivers (
n= 50) of community-dwelling HF patients completed the PPUS-FM, Caregiver Reaction Assessment (CRA) and Hospital Anxiety and Depression Scale (HADS) in this cross-sectional study. Results: Significant correlations emerged among PPUS-FM and (a) CRA-schedule burden (r = .499, p< .01); (b) CRA-financial burden (r = .292, p< .05); (c) CRA-family burden (r = .385, p< .01); (d) CRA-health burden (r = .421; p< .01); and (e) HADS-depression scores (r = −.298, p< .05). Cronbach’s alpha for the PPUS-FM was .89. Conclusions: In this sample, the PPUS-FM had some evidence of construct validity and good internal consistency. However, the respondent burden and unidimensional nature of the PPUS-FM suggest that this tool needs further revision and testing for use with caregivers of HF patients.