This paper shows that yeast can be a host for the replication of a higher eukaryotic viral genome. Brome mosaic virus (BMV) is a member of the alphavirus-like superfamily of animal and plant positive strand RNA viruses. Yeast expressing BMV RNA replication genes 1a and 2a support RNA-dependent replication and transcription of BMV RNA3 derivatives. RNA3 derivatives with the coat gene replaced by a reporter gene expressed that gene in a fashion dependent on 1a and 2a expression in trans and on BMV RNA replication and transcription signals in cis. RNA3 derivatives carrying the yeast URA3 gene complemented ura3- yeast to prototrophy and were maintained as persistent RNA episomes. Thus, all cellular factors essential for BMV RNA replication and transcription must be present in yeast, and yeast genetics should facilitate their identification.