The Hamiltonian, which describes the surface-induced anisotropy for im
purity spin in mesoscopic wires of dilute magnetic alloys, is derived
for the wires with a rectangular cross-section and rough surfaces. We
show that due to the combined effect of the four surfaces of the wire,
the impurity-spin energy spectra are substantially different from tho
se in a semi-infinite host. Moreover, we find that a moderate roughnes
s of the surface enhances the splitting of the impurity-spin energy le
vel. (C) 1998 Elsevier Science Ltd. All rights reserved.