  We combine the resummations for radiative corrections and for the heavy quark
expansion to study the inclusive radiative decay $B \to X_s\gamma$. The
infrared renormalon ambiguity is also taken into account. Including both
theoretical and experimental uncertainties, we determine the allowed domain for
the HQET parameters ${\bar \Lambda}$ and $\lambda_1$ centered at ${\bar
\Lambda}=0.65$ GeV and $\lambda_1=-0.71$ GeV$^2$.
