The paper deals with the history of unsuccessful Russian-Polish military cooperation in the 1660s – 1680s. For approximately twenty years Moscow and Warsaw had been trying to join their military forces against, at first rebellious Ukrainian Cossacks and Crimean Tatars, and then against the Turks too. But all negotiations and attempts to realize plans of military cooperation by joining forces failed because of several reasons. The Polish-Lithuanian Commonwealth, hoping firstly to bring to obedience hetman Peter Doroshenko with Russian support, then tried to recapture invaded by Ottomans Podolia and appropriately wanted Russian troops to be moved there, not between Dnepr and Dniester, as it had been agreed before. Another thing that didn’t satisfy the Polish-Lithuanian side was a parity basis of joining troops (later of mutual exchanging of units), fixed in the text of alliance of December 1667. The Polish-Lithuanian army was becoming weaker because of long wars with Turks, Tatars, Cossacks and therefore needed military support, mainly infantry and artillery, more than Muscovite Russia, which had a more numerous army. That’s why Polish commanders tried to receive under their command Russian units without sending any soldiers and officers of the Commonwealth to the Muscovite army. So Russia finally refused to join its forces with the Polish-Lithuanian army and the new alliance of 1686 stipulated that each signatory was to wage war independently.