Complementary DNA to the genomic RNA of tomato spotted wilt virus (TSWV) was synthesized and cloned in either pUC19 or lambda gt10. Restriction endonuclease maps were constructed from cDNA clones specific for the S and the M RNA segments, extending 3.0 and 5.4 kbp respectively. The nucleotide sequences of the 3' and 5' termini of both RNA molecules were determined. The S and M RNAs contain inverted complementary repeats at their termini, probably involved in RNA replication and in the formation of circular nucleocapsids in virions. The terminal structures of the TSWV genome resemble, in these aspects, those of the Bunyaviridae.