Heart failure (HF) is one of the most common chronic diseases, affecting around 8% of older people, with an incidence rate of 10 per 1000 person-years. Besides ageing and classical cardiovascular risk factors, it is well recognized that HF may be worsened by endocrine alterations. The prevalence of thyroid dysfunction, similarly to HF, increases with increasing age and, 5-15% of the entire older population, especially women, suffer from overt or subclinical thyroid dysfunction. Thyroid and heart share a common embryologic origin and an intimate and complex functional relationship and, cardiovascular effects are the most prominent features of thyroid dysfunction. Not only alterations of thyroid hormone synthesis and release are risk factors for cardiac disease, but a mutual relationship has been documented and dysregulation of thyroid hormones represents also a marker for chronic heart disease. Thus, even mild thyroid dysfunction (either in excess or defect) may lead to the development of HF and may increase the risk of cardiovascular events. Consequently, thyroid dysfunction should be ruled out not only in older HF patients with no other identifiable causes but also in those with known cardiovascular risk factors. Nonetheless, the lack of randomized clinical trials leaves us with several unresolved key issues as also stated in the latest guidelines for the treatment of thyroid dysfunction, .key issues regarding specific criteria and goals of treatment, as also stated. Future large randomized intervention studies, balancing the risk and benefits of thyroid therapy according to the degree of serum TSH and TH alteration, are clearly warranted.