The dependence of the Hall carrier density on bismuth concentration, n, p=f(NBi), in PbSe:Bi:Se/BaF2 films has been studied. The films were grown by vacuum condensation from two independent molecular beams (PbSe:Bi and Se2) mixed directly at the surface of a (111)BaF2 substrate heated to 350°C. The bismuth concentration in the stock was 0–0.3 at. %. Two specific portions can be distinguished in the experimental n, p=f(NBi) dependence. At NBi>0.0375 at. %, the electron density is close to NBi; at low bismuth concentrations, NBi<0.0375 at. %, the linear run of the n=f(NBi) dependence is violated, and the conduction changes to p-type. All the doped films under study are saturated with selenium. This is a necessary condition for obtaining the highest electron densities in the films at NBi corresponding to the linear portion of the n=f(NBi) dependence. The results are discussed in terms of a thermodynamic model of the impurity interaction with intrinsic defects in PbSe, taking into account the amphoteric behavior of bismuth atoms in lead selenide.