  We employ a self-consistent Green's function approach to investigate the
spin-wave relaxation \Gamma(p) in diluted magnetic semiconductors. We find the
trend of the spin-wave relaxation strongly depends on the ratio of the
itinerant and impurity spin densities. For density ratios in the
Ruderman-Kittel-Kasuya-Yosida phase, \Gamma(p) decreases even though thermal
fluctuations increase. On the other hand, in the strong coupling phase, an
interesting peak structure appears. We discuss the implications of our
numerical results for experiments.
