Abstract: Molecular studies have shown that several genes with various functions are induced by drought stresses and that various transcription factors are involved in the regulation of stress-inducible genes. So, this research was carried out on 12 barley (H. nutans Schubl.) varieties, in order to investigate the effect of drought stress and phytohormones on genome structure and its changes in drought tolerant and susceptible barely verities. In drought tolerant and susceptible barely verities, stabile DNA, labile DNA, residual DNA and RNA were extracted. The results showed that the rate of Stabile DNA, Labile DNA and RNA was increased in tolerant variety under drought stress condition. Whereas, in susceptible variety; the rate of those was decreased under drought stress condition. Gibberellic acid plus Kinetin complex induced remarkable increasing on DNA and RNA content in drought susceptible variety, whereas it had little effect on those in drought tolerant variety.