We analyse the $B \rightarrow \tau \nu$ decay in a generic two-Higgs doublet model satisfying the MFV hypothesis. In particular, we analyse under which conditions $\BR(B \rightarrow \tau \nu)$ can be substantially enhanced over its SM value, taking into account the constraints of $K \rightarrow \mu\nu$, $B \rightarrow X_s \gamma$, and $B_s \rightarrow \mu^+ \mu^-$. We find that for large $\tan\beta$ values and Peccei-Quinn symmetry breaking terms of $\cO(1/\tan\beta)$ a sizable ($\sim 50%$) enhancement of $\BR(B \rightarrow \tau \nu)$ is possible, even for $m_H \sim 1$ TeV.

Comment: 5 pages, latex, 4 figs. Discussion of B->Xs gamma bound and corresponding numerical analysis significantly improved. Main conclusions unchanged