  We present 3.6m ESO telescope spectroscopic observations of the system of the
two blue compact dwarf galaxies SBS 0335-052W and SBS 0335-052E. The oxygen
abundance in SBS 0335-052W is 12 + log O/H = 7.13 +/- 0.08, confirming that
this galaxy is the most metal-deficient emission-line galaxy known. We find
that the oxygen abundance in SBS 0335-052E varies from region to region in the
range from 7.20 to 7.31, suggesting the presence of an abundance gradient over
a spatial scale of 1 kpc. Signatures of early carbon-type Wolf-Rayet stars are
detected in cluster 3 of SBS 0335-052E, corresponding to the emission of three
to eighteen WC4 stars, depending on the adopted luminosity of a single WC4 star
in the CIV 4658 emission line.
