  We use QCD sum rules to study the masses of the baryons $\Xi_c$ and $\Xi_b$.
We work with a current where the strange and the light quarks are in a relative
spin zero, at leading order in $\alpha_s$. We consider the contributions of
condensates up to dimension six. For $\Xi_b$ we get $m_{\Xi_{b}}= (5.75\pm
0.25) {\rm GeV}$, and for $\Xi_c$ we get $m_{\Xi_{c}}= (2.5\pm 0.2) {\rm GeV}$,
both in excelent agreement with the experimental values. We also make
predictions to the state $\Omega_b(ssb)$ obtaining m_{\Omega_{b}}= (5.82\pm
0.23) GeV.
