  Preparation of a quantum register is an important step in quantum computation
and quantum information processing. It is straightforward to build a simple
quantum state such as $|i_1 i_2 ... i_n\ket$ with $i_j$ being either 0 or 1,
but is a non-trivial task to construct an {\it arbitrary} superposed quantum
state. In this Paper, we present a scheme that can most generally initialize a
quantum register with an arbitrary superposition of basis states.
Implementation of this scheme requires $O(Nn^2)$ standard 1- and 2-bit gate
operations, {\it without introducing additional quantum bits}. Application of
the scheme in some special cases is discussed.
