Mersalyl (Mersal) is an organomercury compound[1] and mercurial diuretic.

It is only rarely used as a drug, having been superseded by thiazides and loop diuretics that are less toxic because they do not contain mercury.

It features a Hg(II) centre.

Mersalyl was originally adapted from calomel (Hg2Cl2), a diuretic discovered by Paracelsus.

This drug article relating to the cardiovascular system is a stub.