Depolarized light scattering has been used to study the ordering kinetics in a symmetric poly(styrene-b-isoprene) copolymer melt. The depolarized intensity variation with time following a quench from the disordered phase provides an estimate of the grain size which is consistent with the result from the SAXS experiment. The mechanism of grain relaxation is discussed in terms of rotational motions in the mobile environment. The dissolution of the initially ordered structure is much faster (t < 10(2) s) than the ordering process.