Abstract: Abstract: Sensitivities to the azoxystrobin, mefenoxam and metalaxyl of Phytophthora infestans were tested for isolates collected from some areas of two Provinces of Hebei and Jilin in China, using an in vitro radical growth assay on fungcide-amended agar media. All tested 97 isolates from two provinces were sensitive to azoxystrobin. Of 65 isolates from Weichang county of Hebei province, the most ones were mefenoxam-resistant and the percentages of highly-resistant, intermediate-resistant and sensitive were separately 72.3%, 26.2% and 1.5%. Of 35 strains from Changchun city of Jilin province, however, majority was mefenoxam-sensitive and the percentages of sensitive, intermediate-resistant, and resistant strains were 81.3%, 15.6% and 3.1%, respectively. Of the 35 isolates sampled from Weichang county of Hebei province, all isolates were resistant to metalaxyl and the percentage of highly-resistant ones was 91.7%. Of 18 isolates sampled from Changchun city, major isolates were sensitive to metalaxyl and the percentages of sensitive, intermediate-resistant and highly-resistant ones were separately 77.8%, 16.7% and 5.5%. It was also detected that mefenoxam and metalaxyl could make mycelia grow well in the rye medium.