Time for primary review 29 days. Aldosterone (Aldo) plays an essential role in regulation of body sodium and potassium homeostasis by acting on epithelial tissues such as kidney and colon. Since about ten years the two dogmas which classically characterize Aldo, i.e., a synthesis in adrenal glands only and an action exclusively in epithelial tissues, have been challenged. Namely, Aldo receptors are present in the heart and specific actions of Aldo can be demonstrated in this organ. This suggests that cardiac tissue may be a genuine target for Aldo. Moreover, there are indications that an increase of plasma Aldo may be a risk factor in cardiovascular pathologies. For example, the CONSENSUS multicentric study has shown a relationship between plasma Aldo concentration and mortality in patients with congestive heart failure [1] The very recent discovery of Aldo synthesis in rat heart [2] brings a new step to the evolution of our ideas concerning the physiology of this hormone. This demonstrates the existence of an Aldo tissular system – i.e., the presence in a cell or a group of cells of all the biochemical elements necessary for synthesis of a hormone and its specific receptors – making it possibly a local autocrine or paracrine action. This review makes the point of the literature dealing with effects and synthesis of Aldo in the heart. ### 2.1 The intracellular mineralo-receptor Aldo effects are mediated by binding of the hormone to its specific receptor: the mineralocorticoid receptor (MR). The MR is a nuclear zinc-finger transcription factor and forms a subfamily with glucocorticoid receptors (GR), progesterone and androgen receptors. The functional and structural organization of this receptor family displays three main domains: the variable N-terminal region, a well-conserved cysteine-rich DNA-binding domain (=90% amino acid identity) and a C-terminal steroid binding domain (=50% amino acid identity). In addition to epithelial tissues (kidney, … * Corresponding author. Tel.: +33-144-631-727; fax: +33-148-742-315 delcayre{at}infobiogen.fr