A mineralocorticoid is any of a family of steroid hormones characterized by their similarity to aldosterone and their influence on salt and water metabolism. Both mineralocorticoids and glucocorticoids are classed as corticosteroids and originate in the cortex of the adrenal glands.

The only endogenous mineralocorticoid is aldosterone, although a number of hormones (mainly progesterone) have mineralocorticoid function. Aldosterone acts on the kidneys to provide active reabsorption of sodium and an associated passive reabsorption of water, as well as the active secretion of potassium in the principal cells of the cortical collecting tubule and active secretion of protons via proton ATPases in the lumenal membrane of the intercalated cells of the collecting tubule.