Molecular and mass characteristics of fractions of polystyrene scintillators with para-terphenyl (2%) and 4,4-distirilbyphenyl (0.007%) admixtures are investigated. It is shown that the organic luminophors being used do not essentially affect the polymer chain topology at the stage of scintillator preparing and during polymerization a molecular structure is formed, which is characterstic for polystyrene obtained by bulk thermal polymerization. It is found that the large samples of scintillators obtained by the technology used are sufficiently homogeneous. 10 refs.; 1 fig.