A gauge-fixed action is constructed for the free heterotic string based on the bosonic string and the Neveu-Schwarz-Ramond (NSR) superstring by the Becchi-Rouet-Stora-Tyutin approach. The field theory gives a balance condition; it replaces the Gliozzi-Scherk-Olive projector in the NS sector to eliminate the tachyons and to ensure that the states have the correct spin statistics. At the massless level we get a ten-dimensional linearized supergravity, a ten-dimensional linearized super-Yang-Mills field with the gauge group E/sub 8/ x E/sub 8/ or Spin(32)/Z/sub 2/, a dilaton, an interesting dilatonlike Majorana-Weyl spinor, and so on.