For the SOS model defined by the Hamiltonian H(phi) = 1/2SIGMA[x,x'] \
phi(x) - phi(x')\ + h SIGMA(x)phi(x), where phi(x), phi(x') is-an-elem
ent-of {1, 2,...}, h>0, x is-an-element-of Z(d), d greater-than-or-equ
al-to 2, it is shown that in the low-temperature region an infinite se
quence of first-order phase transitions takes place when h --> 0 and t
he temperature is fixed.