  The s-wave meson-nucleon interaction in the $S = -1$ sector is studied by
means of coupled-channel Lippmann Schwinger equations, using the lowest order
chiral Lagrangian and a cut off to regularize the loop integrals. The method
reproduces succesfully the $\Lambda (1405)$ resonance and the $K^- p \to K^- p,
\bar{K}^0 n, \pi^0 \Lambda, \pi^0 \Sigma, \pi^+ \Sigma^-, \pi^- \Sigma^+$ cross
sections at low energies. The inclusion of the $\eta \Lambda, \eta \Sigma^0$
channels in the coupled system is found very important and allows a solution in
terms of only the lowest order Lagrangian.
