Para rubber tree (Hevea brasiliensis) produces latex and is an economically important tree in Viet Nam. In a 2013-15 survey, powdery mildew was observed mainly from February to May in many intensively cultured areas countrywide, including Son La, Lai Chau, Dak Lak, Binh Phuoc, Dong Nai, and Vung Tau provinces. The fungus covered both sides of young and mature leaves. Heavily infected trees had deformed leaves or defoliated early, resulting in yield reductions up to 30%. Based on morphological characteristics, sequence analysis of the rDNA internal transcribed spacer region and pathogenicity, the fungus was identified as E. quercicola. This fungus has a broad host range and a widespread distribution in tropical and subtropical Africa, Asia, and South America. This is thought to be the first report of powdery mildew caused by E. quercicola on para rubber tree in Viet Nam.