This report describes isolation of virus particles from plants of rice, maize, wheat and sorghum with symptoms of dwarfing collected from two provinces of China, purification of double-stranded RNA (dsRNA) from the virus particles, and synthesis of full-length cDNAs of genome segments 9 (S9) and 10 (S10) by reverse transcription-polymerase chain reaction (RT-PCR). Sequence analysis showed that the S9 sequences of the Chinese isolates and a Japanese rice black-streaked disease virus (RBSDV) isolate were very similar (89.1-89.6% homology at nucleotide level and 92.3-92.9% and 95.8-98.6% homology at amino acid level for ORF1 and ORF2, respectively). Analogical similarity was found also for the S10 sequences of the isolates under comparison: 93.0-95.4% homology at nucleotide level and 96.2-97.0% homology at amino acid level. However, there was a relatively lower similarity for S9 and S10 segments ofthe Chinese isolates and an Italian maize rough dwarf virus (MRDV) isolate. The phylogenetic analysis indicated that the Chinese isolates that infect rice, maize, wheat and sorghum and cause similar symptoms could represent the same virus species, RBSDV.