  We study analytic integrable deformations of the germ of a holomorphic
foliation given by $df=0$ at the origin $0 \in \mathbb C^n, n \geq 3$. We
consider the case where $f$ is a germ of an irreducible and reduced holomorphic
function. Our central hypotheses is that, {\em outside of a dimension $\leq
n-3$ analytic subset $Y\subset X$, the analytic hypersurface $X_f : (f=0)$ has
only normal crossings singularities}. We then prove that, as germs, such
deformations also exhibit a holomorphic first integral, depending analytically
on the parameter of the deformation. This applies to the study of integrable
germs writing as $\omega = df + f \eta$ where $f$ is quasi-homogeneous. Under
the same hypotheses for $X_f : (f=0)$ we prove that $\omega$ also admits a
holomorphic first integral. Finally, we conclude that an integrable germ
$\omega = adf + f \eta$ admits a holomorphic first integral provided that: (i)
$X_f: (f=0)$ is irreducible with an isolated singularity at the origin $0 \in
\mathbb C^n, n \geq 3$; \, (ii) the algebraic multiplicities of $\omega$ and
$f$ at the origin satisfy $\nu(\omega) = \nu (df)$. In the case of an isolated
singularity for $(f=0)$ the writing $\omega = adf + f \eta$ is always assured
so that we conclude the existence of a holomorphic first integral. Some
questions related to Relative Cohomology are naturally considered and not all
of them answered.
