Caracterization of the FAR-IR emission of QSOs is an important goal of
 ISO in order to derive their dust content, the origin of dust heating
 and the possible presence of strong starbursts comparable to those of
 ultraluminous IR galaxies. We propose here a dedicated study of two
 subclasses of quasars with signposts of high dust content and/or
 starbursts: strong optical FeII emitters and Broad Absorption Lines
 (BAL) QSOs. Since there is a correlation between strong FeII and
 FAR-IR emissions in low redshift QSOs and IR galaxies, one possible
 explanation of strong FeII emission is supernovae remnants associated
 with strong starbursts. The broad absorption lines of BAL QSOs could be
 formed in the gas accelerated through radiation pressure and dust after
 a starburst. We will also include a few QSOs with "associated"
 absorption systems of narrow lines at the redshift of the QSOs, since
 they could be in an evolutionnary stage related to BALs. Our sample
 includes both QSOs with z ~1-2 and of moderate z (0.1-0.4) for
 comparison. ISOPHOT should detect them in the FAR-IR, even at high
 redshift if their FAR-IR luminosity compares to that of IR ultraluminous
 galaxies, and will thus provide the FOR-IR luminosity, dust mass and
 temperature.
 CII and OI fine structure lines are among the best tracers of the large
 amount of warm and dense neutral gas caracterictic of violent starbursts.
 We propose to search them in the few members of our sample with
 continuum fluxes strong enough (detected by IRAS) and in a few other
 strong IR QSOs for comparison.