Heart failure is one of the major health threats in Western societies, and its prevalence is steadily increasing. Many data show the important impact of sex (biological) and gender (sociocultural) differences on most aspects (diagnosis, etiology, treatments, and outcomes) of heart failure. For example, compared to men, women with heart failure are older, have more co-morbidities, and develop different phenotypes of heart failure. Postpartum cardiopathy is unique in women. The iatrogenic effects of cancer therapies are more frequent among women compared to men. Currently, the integration of sex and gender differences into the therapy of heart failure is rare. Consequently, women derive disadvantages from a nonspecifically adapted therapy for heart failure, get worse outcomes, and have more iatrogenic adverse effects than men. This situation is medically unfortunate and increases medical expenditures. A sex-guided approach to the correct evaluation of patients with heart failure should become the cornerstone for the correct management of these patients.