  In this talk a brief review of several problems involving systems with
strangeness is made. In the first place one shows how the $\Lambda (1405)$,
$\Lambda(1670)$ and $\Sigma(1620)$ states, for $S = -1$, and the $\Xi(1620)$
for $S= -2$ are generated dynamically in the context of unitarized chiral
perturbation theory. The results for the $\bar{K}N$ interaction are then used
to evaluate the $K^- d$ scattering length. Results obtained for the kaon
selfenergy in a nuclear medium within this approach, with application to $K^-$
atoms, are also mentioned. Finally a few words are said about recent
developments in the weak decay of $\Lambda$ hypernuclei and the puzzle of the
$\Gamma_n/\Gamma_p$ ratio.
