  We present a short review of the abundances in the atmospheres of SB2 systems
with Mercury-Manganese (HgMn) primaries. Up to now a careful study has been
made for both components of 8 out of 17 known SB2 binaries with orbital periods
shorter than 100 days and mass ratio ranging from 1.08 to 2.2. For all eight
systems we observe a lower Mn abundance in the secondary's atmospheres than in
the primary's. Significant difference in the abundances is also found for some
peculiar elements such as Ga, Xe, Pt. All secondary stars with effective
temperatures less than 10000 K show abundance characteristics typical of the
metallic-line stars.
