From 380S particles of Berne virus (proposed family Toroviridae) one species of polyadenylated RNA was isolated. Using agarose gel electrophoresis its length was estimated as 20 kb or greater. When assayed under hypertonic transfection conditions genomic RNA was found to be infectious; RNase treatment destroyed the infectivity. The positive polarity of the molecule was confirmed by filter spot hybridization using cDNA prepared against poly(A)-selected RNA from infected cells. In embryonic mule skin cells infected with Berne virus the presence of five virus-specific, polyadenylated RNA species of 7.5, 2.1, 1.4, 0.8 and at least 20 kb was demonstrated. In vitro translation of the 7.5, 2.1 and 0.8 kb RNAs followed by immunoprecipitation showed that they encode a 151K product (possibly the precursor to the peplomer proteins), the envelope protein and the nucleocapsid protein, respectively.