  We analyse the stellar content of a large number of HII galaxies from the
continua and absorption features of their spectra using population synthesis
methods, in order to gain information about the star formation histories of
these objects.
  We find that all galaxies of our sample contain an old stellar population (>=
1 Gyr) that dominates the stellar mass, and in a majority of these we also
found evidence for an intermediate-age population >= 50 Myr apart from the
presently bursting, ionizing young generation <= 10^7 yrs
