B-type natriuretic peptide (BNP) and N-terminal-proBNP (NT-proBNP) are increasingly recognized as prognostic markers in patients with acute coronary syndrome (ACS). The need for novel and more effective tools for risk assessment cannot be more emphasized than in older patients with ACS given their atypical presentation, multiple comorbidities, and higher risk for mortality and morbidity. Accurate interpretation of B-type NP values in older patients with ACS, however, may be confounded by several aging-related physiologic changes. Advanced age, reduction in body mass, and kidney function and anemia have been associated with higher BNP and NT-proBNP concentrations, and may create challenges with interpreting NP levels in the elderly. This review highlights the need to better understand the physiology of BNP and NT-proBNP in older individuals and their prognostic value in older patients with ACS.