  We calculate the form factors and the coupling constant in the $\rho D^* D^*$
vertex in the framework of QCD sum rules. We evaluate the three point
correlation functions of the vertex considering both $\rho$ and $D^*$ mesons
off--shell. The form factors obtained are very different but give the same
coupling constant: $g_{\rho D^* D^*} = 6.6 \pm 0.31$. This number is 50% larger
than what we would expect from SU(4) estimates.
