Let $R$ be a commutative Noetherian ring, and let $\mathbf{x}= x_1,
\ldots, x_d$ be a regular $R$-sequence contained in the Jacobson radical
of $R$. An ideal $I$ of $R$ is said to be a monomial ideal with respect to
$\mathbf{x}$ if it is generated by a set of monomials $x_1^{e_1}\ldots
x_d^{e_d}$. The monomial closure of $I$, denoted by $\widetilde{I}$, is
defined to be the ideal generated by the set of all monomials $m$ such
that $m^n\in I^n$ for some $n\in \mathbb{N}$. It is shown that the
sequences $\mathrm{Ass}_RR/\widetilde{I^n}$ and $\mathrm{Ass}_R\widetilde{I^n}/I^n$,
$n=1,2, \ldots,$ of associated prime ideals are increasing and ultimately
constant for large $n$. In addition, some results about the monomial ideals
and their integral closures are included.