  In this talk, we consider the interplay of fundamental and matter-induced
T-violating effects in neutrino oscillations in matter. We present a simple
approximative analytical formula for the T-violating probability asymmetry for
three flavor neutrino oscillations in matter with an arbitrary density profile.
We also discuss some implications of the obtained results. Since there are no
T-violating effects in two flavor neutrino case (in the limit of vanshing
$\theta_{13}$ or $\Delta m_{21}^2$, the three flavor neutrino oscillations
reduces to the two flavor ones), the T-violating probability asymmetry can, in
principle, provide a way to measure $\theta_{13}$ and $\Delta m_{21}^2$.
