  We perform a lattice study of heavy baryons, containing one ($\Lambda_b$) or
two $b$-quarks ($\Xi_b$). Using the quenched approximation we obtain for the
mass of $\Lambda_b$ $$ M_{\Lambda_b}= 5.728 \pm 0.144 \pm 0.018 {\rm GeV}.$$
The mass splitting between the $\Lambda_b$ and the B-meson is found to increase
by about 20\% if the light quark mass is varied from the chiral limit to the
strange quark mass.
