We present the results of high S/N long-slit spectroscopy with the Multiple Mirror (MMT) and the SAO 6-m (BTA) telescopes, optical imaging with the Wise 1-m telescope and HI observations with the Nancay Radio Telescope of the very metal-deficient (12+log(O/H)=7.64) luminous (M_B_=-18.1mag) blue compact galaxy (BCG) HS 0837+4717.