Field screening of 25 indigenous and exotic clones against powdery mildew (Oidium heveae) was carried out for four consecutive years relying on natural disease incidence. The phenotypic expression of symptom severity in terms of percent disease intensity (PDI) was used to compare the clones. The disease incidence of clones varied significantly in different years as evidenced by the significant clone x year interaction. Two methods viz, mean and CV of genotypes and Huhns rank sum were used to identify the comparatively stable genotypes. The clones RRII 208 and PB 310 were found to have less disease intensity with greater stability over the years based on mean and CV. As per Huhns rank sum method, clones SCATC 93-114, RRIM 703, Hai Ken 1, RRII 208, RRII 5 and PB 310 were identified as stable sources of resistance.