Rubber tree (Hevea brasiliensis Muell. Arg.), a tropical perennial crop species which produces natural rubber widely used in industries, is the most important economic crop in tropical areas of China. Rubber trees exhibiting symptoms of stem fasciation; irregular bending of branches, witches’ broom, little leaves on abnormal branches and early withering of abnormal branches (Figure 1) were observed during a field survey conducted in December 2011 in Hainan Province, China. The disease was named rubber tree stem fasciation (RTSF). The incidence rate of RTSF is less than 3% in surveyed areas. Former studies have reported similar symptoms associated with phytoplasmas in rubber tree on the basis of transmission electron microscope (Chen et al. 1991). The objectives of this work were to detect and identify the agent associated with the symptomatic rubber trees and to carry out molecular characterization of the pathogen. Samples of symptomatic (21) and asymptomatic (6) rubber trees were collected in three locat...