  We investigate the strong vertices among $\Lambda_b$, nucleon and $B$ meson
as well as $\Lambda_c$, nucleon and $D$ meson in QCD. In particular, we
calculate the strong coupling constants $g_{\Lambda_bNB}$ and $g_{\Lambda_cND}$
for different Dirac structures entered the calculations. In the case of
$\Lambda_cND$ vertex, the result is compared with the only existing prediction
obtained at $Q^2=0$.
