  We study the inclusive charmless semileptonic decay of $\Lambda_b$,
$\Lambda_b \to X_u l \nu_l$, in the framework of heavy quark expansion and find
that the rate is substantially enhanced by spectator effect. We obtain $Br(b
\to X_u l \nu_l)$ to be $1.13 \times 10^{-3}$ for $|V_{ub}| = 3.3 \times
10^{-3}$. We discuss our result in light of the recent LEP measurements of the
charmless semileptonic branching ratio where such enhancement was not taken
into account in extracting $|V_{ub}|$.
