By using the ma thod of inoculating o n hypoco ty l w o und of the dif ferential hostsw ith standard physio logical races, 10 st rains of phytoph thora megag perma w ere used fo ridenti fica tion. Sev en st rains of them show ed same reactio n to dif ferential ho st s co usingHa ro soy to be susceptible a nd the o ther host w ere resi stance to the 7 races. The resul tsw as compa red wi th that o f the standard phy siological races a nd w e co ncluded that the 7st rains w ere No. 1 of phy to phtho ra megasperma.