During the last few years, it became clear that electron interference phenomena strongly modify the conductance of disordered systems. In thin metal films, this interference produces an anomalous low temperature magneto-resistance which enables to obtain detailed information about the inelastic, spin-orbit and magnetic scattering mechanisms. In a multiply-connected geometry, the interference leads to magnetoresistance oscillations. In long metal cylinders, only the oscillations which are not destroyed by impurity averaging, can be observed (flux period h/2e). In single loops, the original Aharonov-Bohm oscillations with flux period h/e are also present. A review will be presented of recent experimental results obtained for quasi two-dimensional plane films, cylinders, rings and arrays.