The DTA method has been used for determination of the initial crystallization temperatureTA of the vitreous selenium with admixtures of sulphur (crystallization inhibitor) and tellurium (crystallization catalyst). It was found that both admixtures raise the value ofTA. The obtained results suggest that each foreign atom distorts the structures of the chain in vitreous selenium and consequently inhibits the nucleation. The values of the heat of transformation and degree of crystallization have been also determined.