By the eighteenth century the game had fallen out of popularity, and due to the exact rules never having been written down we do not know precisely how the game was played. However a number of reconstructions of the game have been made, primarily on the basis of books describing playing strategy and references in period literature.
Primero is generally considered to be the direct ancestor of the modern game of poker.
It is thought that primero is closely related to the game of primo visto, although their exact relationship is unknown.