The article describes the problem of political system agreement which was drawn up between communist government and opposition during ‘Round Table’ sessions without any demand of resignation from socialist system. The agreement described in article recognizes that socialist parliamentary democracy will be a system which is based on values and principles such as: evolutionary character of transformation; departure from Marxist ideology as system of values in exercised power; leading role of PUWP is kept (the leadership is in the hands of president as a new-created office); political pluralism – freedom to form associations (but not multi-partial system); keeping all previous international alliances etc. New system of leading state bodies is created – the office of president is re-established as well as Senate as a second chamber, but Sejm kept its leading position. The socialist parliamentary democracy was practically only a short – term structure: the December amendment in 1989 terminated its functioning.