you can set the overlay and remember picture option to the tikzpicture:
\documentclass{beamer} \usepackage{tikz} \begin{document} \begin{frame} \begin{tikzpicture}[overlay,remember picture] \draw (0,0) circle (1cm); \end{tikzpicture} \end{frame} \begin{frame} \begin{tikzpicture}[overlay,remember picture] \draw (0,0) circle (1cm); \draw (2,2) circle (2cm); \end{tikzpicture} \end{frame} \end{document}
With these options you have also access to the current page anchor, which allows for cool stuff like:
\documentclass{beamer} \usepackage{tikz} \begin{document} \begin{frame} \begin{tikzpicture}[overlay,remember picture,every node/.style={draw,minimum size=2.5cm,circle}] \node [anchor=east] at (current page.east){}; \node [anchor=west] at (current page.west){}; \node [anchor=north] at (current page.north){}; \node [anchor=south] at (current page.south){}; \end{tikzpicture} \end{frame} \begin{frame} \begin{tikzpicture}[overlay,remember picture,every node/.style={draw,minimum size=2.5cm,circle}] \node [anchor=east] at (current page.east){}; \node [anchor=west] at (current page.west){}; \node [anchor=north] at (current page.north){}; \node [anchor=south] at (current page.south){}; \node at (current page.center){}; \end{tikzpicture} \end{frame} 