  For a ring $R$ with an automorphism $\sigma$, an $n$-additive mapping
$\Delta:R\times R\times... \times R \rightarrow R$ is called a skew
$n$-derivation with respect to $\sigma$ if it is always a $\sigma$-derivation
of $R$ for each argument. Namely, it is always a $\sigma$-derivation of $R$ for
the argument being left once $n-1$ arguments are fixed by $n-1$ elements in
$R$. In this short note, starting from Bre\v{s}ar Theorems, we prove that a
skew $n$-derivation ($n\geq 3$) on a semiprime ring $R$ must map into the
center of $R$.
