Abstract: The physiological races of 40 Phytophthora parasitica var. nicotianae strains collected from Fuling, Pengshui, Shizhu in Chongqing were isolated, and identified by zoospore suspension inoculation and TTC (2, 3, 5-triphenyltetrazolium chloride) color reaction. The results showed that all the 40 strains were highly pathogenic to tobacco cultivar L8 but not to Nicotiana nesophila and all of them presented red reaction in TTC medium. It indicated that all the strains belong to physiological race 1.