Let R be a prime ring
with no nonzero nil ideals and suppose that d is a derivation of R such that
d(xn) = 0, n = n(x) ≧ 1, for all x ∈ R. It is shown that either d = 0 or
R is an infinite commutative domain of characteristic p≠0 and p∖n(x) if
d(x)≠0.