A virus detected in symptomatic Trifolium pratense L. plants in the Czech Republic had bacilliform virions which in thin sections occurred solely in phloem tissues and measured 220–500 nm by 30–31.5 nm. The virus was mechanically transmitted to Nicotiana occidentalis Wheeler, accession 37B. The partial nucleotide sequence (540 bp; accession number JX069965) with similarity to open reading frame III of the badnavirus genome was amplified from total genomic DNA, extracted from the plants. The new sequence had 74.4% nucleotide identity to that of Ananas comosus endogenous virus in the polyprotein gene covering reverse transcriptase. The results suggest that the Czech isolate from clover should be regarded as a new member of the genus Badnavirus, for which the name Red clover bacilliform virus is suggested. This is the first report of a tentative member of Badnavirus genus occurring in forage crops.