Heart Failure with Preserved Ejection Fraction (HFpEF) is one of the most frequent causes of heart failure in the world's population (about 19-55%), and is commonly associated with a high rate of hospitalization (almost 70-80%) and with increased mortality (40-50% in a 5-year timeframe). The elderly are more often affected, with higher rates of hospitalizations than young people, and currently almost 70% of the population aged 65 years old has HFpEF. An increase in cardiomyocyte stiffness, thus resulting in diastolic dysfunction, increased filling pressures and heart failure with preserved ejection fraction are characteristics features of the disease. In addition, among the various causes of HFpEF, cardiac amyloidosis (CA) can provoke diastolic dysfunction and increased wall stiffness directly from intercellular deposition of insoluble proteic substances and their toxic activity. Totally, almost 30 different proteins are able to form deposits, but the most frequently involved are transthyretin and misfolded monoclonal immunoglobulin light chains, which bring to two clinical conditions called transthyretin amyloidosis (ATTR) and light-chain amyloidosis (AL). Although there has been increasing attention on ATTR-CA in recent years, the actual prevalence remains underestimated, especially in people of advanced age, as well as its real impact as a cause of HFpEF, and only data derived from autoptic exams are currently available. Moreover, CA itself often mimics HFpEF, and some conflicting data on the use of predictive scores are described in the literature. The close relationship between HFpEF and CA, especially in older population and the main pathophysiological mechanisms which bond these two conditions are described in this focused review. The need to screen red flags for ATTR-CA in elderly patients with HFpEF is urgently advised, because a prompt recognition of the disease can optimize the approach to the disease with an early therapeutic, life-saving choice.