The 3′-terminal sequences of the 10 double-stranded RNA genome segments of bluetongue virus (serotypes 10 and 11) were determined. The double-stranded RNAs were 3′ labeled with [5′-32P]pCp and resolved into 10 segments by electrophoresis. After denaturation, the two complementary strands of segments 4 through 10 were resolved into fast- and slow-migrating species by polyacrylamide gel electrophoresis, and their 3′ end sequences were determined. Complete RNase T1 digestion of the individual 3′-labeled double-stranded RNA segments yielded two labeled oligonucleotides, one of which migrated faster than the other on 20% polyacrylamide-7 M urea gels. Sequence analyses of the two oligonucleotides of segments 4 through 10 confirmed the corresponding RNA sequence data results. The 3′-terminal sequences of the fast-migrating RNA species were (HO)CAAUUU…; those of the slow-migrating RNA species were (HO)CAUUCACA…. Similar results were obtained for double-stranded RNA from bluetongue-virus serotypes 10 and 11. Beyond the common termini, the sequences for each segment varied considerably.