Molecular characterstics of Chrysanthemum B Carlavirus (CVB) isolated from chrysanthemum (Dendranthema grandiflora Kitam) in Indonesia. Chrysanthemum B Carlavirus (CVB) belongs to Carlavirus genus which type species is Carnation latent virus (CLV). Since CVB is considered a new plant virus in chrysanthemum plantation in Indonesia, a study on its molecular characters is required. The objectives of the study are: 1) to determine molecular characters of CVB; 2) to study genetic diversity among CVB isolates collected from different geographic regions in Indonesia. The research activities cover virus purifications, electron microscope observation, coat protein analysis by SDS PAGE, and nucleic acid analysis. The result of virus purification demonstrated a high purity level with ratio value of A260/A280 =1.22. The total pure virus produced from 200 g of fresh material is 6.250 mg. Purified virus preparation yielded rather straight rod and flexuous virus particles of about 685 nm long and 12 nm wide. Coat protein analysis with sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed specific protein band of approximately 34 kDa. Specific DNA fragment of 739 bp was successfully amplified from chrysanthemum infected by CVB Cianjur, Medan, Malang and Bali isolates. CVB isolated from Cianjur, Medan, Malang and Bali have similarity 85-99%. Based on analysis using PAUP 4.10 program, Cianjur, Medan, Malang and Bali isolates belong to the same group with CVB isolates originated from India (Chattisgarh and Jammu isolates). Cianjur isolate has close relationship to Medan isolate, however Bali isolate showed a close relationship with Malang isolate.