  We calculate the decay rate for inclusive $B \rightarrow {\tau}{\nu}X$ decays
in a two Higgs doublet model using heavy quark expansion and operator product
expansion. Combined with the recent measurement of Br($B \ra \tau \nu X$), we
find a limit $\tan \beta < 0.58 m_H/\mbox{GeV}$ at 90\%\ C.L..
