  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.. 
$B \rightarrow {\tau}{\nu}X$ decays in a two Higgs doublet model