  The phenomenology associated with line profile variations in delta Scuti
stars is reviewed. The three main techniques adopted to detect pulsation modes,
i.e., the pixel-by-pixel analysis, the analysis of the moment time series and
the Fourier Doppler Imaging are presented and discussed. Their application to
the observational data has allowed the reliable detection of several pulsation
modes, many of them not detectable with photometric observations. The need of
better coordination of simultaneous spectroscopic and photometric campaigns in
order to get the complete pulsation spectra of these stars is pointed out. The
observation in different campaigns of the same objects has proved that dramatic
changes in the mode amplitudes are quite common, even in a couple of years (and
maybe less). In the last part of the paper a recent approach to the mode
detection by direct fit of line profile variations in multiperiodic pulsators
is described.
