  The phase shift of the O(4) symmetric $\phi^4$ theory in the symmetric phase
is calculated numerically using the relation between phase shift and energy
levels of two-particle states recently derived by L\"{u}scher. The results
agree with the prediction of perturbation theory. A practical difficulty of the
method for a reliable extraction of the phase shift for large momenta due to
the necessity of a precise determination of excited two-particle energy levels
is pointed out.
