Springer-Verlag 2008 Potato rough dwarf virus (PRDV) was originally described in Argentina (2) while potato virus P (PVP) was first reported from Brazil (4). These viruses were essentially indistinguishable in test plant reactions when inoculated onto 21 different solanaceous species (7). Of the 10 sola- naceous species susceptible to both PRDV and PVP, the majority did not display symptoms. Only Nicotiana meg- alosiphon and N. occidentalis showed systemic symptoms consisting of leaf deformations, leaf rugosity and/or inter- veinal chlorosis. Six of the 7 potato varieties tested were susceptible to both PRDV and PVP, but visible symptoms consisting of plant stunting and the aforementioned leaf symptoms were only evident in second-generation plants of the potato cvs. Primicia and Sierra Volcan infected by PRDV (7). When amplicons were obtained from PRDV- and PVP- infected tissue using carlavirus-specific primers for poly- merase chain reaction (PCR) these viruses were initially classified as members of tentative species of the genus Carlavirus (6). Recent biological, serological and partial sequence comparisons have suggested that PRDV and PVP should be considered strains of the same carlavirus species (7, 8). This report describes the complete genomes of PRDV and PVP, and their relationships with other carlaviruses. The PVP and PRDV isolates studied were those from the potato cvs. Baronessa and Sierra Volcan( 7). They were inoculated onto plants of Nicotiana occidentalis, and one month after inoculation, leaves of these plants were used for virion purification following the International Potato Center protocol (CIP Training Manual, Techniques in Plant Virology). RNA extracted from purified PRDV and PVP particles was used for cDNA synthesis using the Universal RiboClone cDNA Synthesis System (Promega, USA). After cloning of cDNA in pZErO-2 (Invitrogen, USA), the recombinant clones were sequenced using SP6 and T7 vector-specific primers in a MegaBACE 750 Sequencer (GE, Sweden) with DYEnamic ET Dye Terminator Cycle Sequencing kits (GE, Sweden). The 5 0 rapid amplification of cDNA ends (RACE) method was employed to obtain the 5 0 -terminal ends of both viral genomes (9). Amplicons were cloned into a pGEM-T vector (Promega, USA). At least four independent clones were sequenced for each virus as described above. To obtain the complete sequence of the 3 0 non-translated region (NTR), we used a tailed oligo-dT (''oligo-dTail''; 5 0 -GCTGAAGACGGCCTATGTGGCC (T)16-3 0 ) as a reverse primer for PCR amplification, fol-