  Precise measurements of semileptonic kaon decay rates at KLOE provide the
measurement of the CKM mixing matrix element \vus\ and information about lepton
universality. Leptonic kaon decays provide an independent measurement of
$\abs{\vus}^2/\abs{\vud}^2$, through the ratio $\Gamma(K\to\mu
\nu)/\Gamma(\pi\to\mu \nu)$. These measurements, together with the result of
$|\vud|$ from nuclear $\beta$ transitions, provide the most precise test of CKM
unitarity, allowing the universality of lepton and quark weak couplings to be
tested. After the completion of the KLOE data taking, the proposal of a new run
with an upgraded KLOE detector, KLOE-2, at an upgraded Dafne machine has been
accepted by INFN and it is now starting. Present results from KLOE and future
perspectives from KLOE-2 are reported.
