\documentclass{article}
\usepackage{algorithmic}

\begin{document}

\begin{algorithmic}[1]
  \IF{first condition}
    \RETURN one
  \ELSIF{second condition}
    \RETURN two
  \ENDIF
  \STATE do something
  \STATE and another
  \IF{third condition}
    \FORALL{items}
      \STATE do some more
    \ENDFOR
    \RETURN three
  \ELSE
    \RETURN four
  \ENDIF
\end{algorithmic}

\end{document}