  In this work I briefly review some of the effects of hyperons on the
properties of neutron and proto-neutron stars. In particular, I revise the
problem of the strong softening of the EoS, and the consequent reduction of the
maximum mass, induced by the presence of hyperons, a puzzle which has become
more intringuing and difficult to solve due the recent measurements of the
unusually high masses of the millisecond pulsars PSR J1903+0327 ($1.667\pm
0.021 M_\odot$), PSR J1614-2230 ($1.97 \pm 0.04 M_\odot$), and PSR J0348+0432
($2.01 \pm 0.04 M_\odot$). Some of the solutions proposed to tackle this
problem are discussed. Finally, I re-examine also the role of hyperons on the
cooling properties of newly born neutron stars and on the so-called r-mode
instability.
