Using DC are optical emission spectrometry, B and Cd have been estimated in MgF2 in the concentration range, 1-20 ppm. An on-line background correction procedure has been developed to obtain net peak intensities for B 249.77 nm, Cd 228.80 nm and Ga 241.87 nm (internal standard) lines. The background corrected peak intensities provided linear calibration plots. The mean relative standard deviation of the method is found to be 11.1% for B and 9.8% for Cd.