Short defective RNAs (D-RNAs) associated with tomato black ring virus (TBRV) were isolated, cloned and sequenced. As a result, two types of D-RNAs associated with different TBRV isolates were identified. Both types were derived from RNA1. The first one contained sequences from the 5' and 3' untranslated regions (UTR) and from the 5' region of a single large open reading frame. The second one included a portion of the coding region for the RNA-dependent RNA polymerase flanked by a short fragment of the 5' UTR and the entire 3' UTR. The possible nature and origin of these RNA species is discussed.