The time evolution of a spin operator Sjx(t) in a nearest-neighbor S=1/2 semi-infinite XY chain is considered at T=. It is shown that the surface spin relaxes very differently compared to the subsurface spin, which already behaves like a bulk spin. The transition from surface to bulk dynamics is discussed using the recurrence-relations method of solving the Heisenberg equation of motion. © 1991 The American Physical Society.