  In this article, we study the $\Lambda_c$ and $\Lambda_b$ baryons in the
nuclear matter using the QCD sum rules, and obtain the in-medium masses
$M_{\Lambda_c}^*=2.335\,\rm{GeV}$, $M_{\Lambda_b}^*=5.678\,\rm{GeV}$, the
in-medium vector self-energies $\Sigma^{\Lambda_c}_v=34\,\rm{MeV}$,
$\Sigma^{\Lambda_b}_v=32\,\rm{MeV}$, and the in-medium pole residues
$\lambda_{\Lambda_c}^*=0.021\,\rm{GeV}^3$,
$\lambda_{\Lambda_b}^*=0.026\,\rm{GeV}^3$. The mass-shifts are
$M_{\Lambda_c}^*-M_{\Lambda_c}=51\,\rm{MeV}$ and
$M_{\Lambda_b}^*-M_{\Lambda_b}=60\,\rm{MeV}$, respectively.
