You can install ST 8.5 using Domino 8.5.0, but if you want Domino 8.5.x see these links: http://www-10.lotus.com/ldd/stwiki.nsf/dx/Sametime_8.5_issues_on_Domino_8.5.1 http://www-01.ibm.com/support/docview.wss?uid=swg21418535