CP-violation in neutrino oscillations

We study in a quantitative way CP-violating effects in neutrino oscillation experiments in the light of current and future data. Different scenarios with three and four neutrinos are worked out in detail including matter effects in long baseline experiments and it is shown that in some cases CP-violating effects could affect the analysis of a possible measurement. In particular in the three neutrino case we find that the effects can be larger than expected, at least in long-baseline $\nu_\mu\to\nu_e$. Moreover, measuring these effects could give useful information on the solar oscillation frequency. In four neutrino scenarios large effects are possible both in the $\nu_\mu\to\nu_\tau$ and $\nu_\mu\to\nu_e$ channels of long-baseline experiments, whereas short-baseline experiments are affected only marginally.