The coat protein (CP) gene from potato virus Y (Hungarian isolate, PVY-H) was engineered into Agrobacterium tumefaciens binary vector for expression in different tobacco lines. Four different Nicotiana tabacum breeding lines were transformed and the integration of the CP gene was confirmed by PCR technique using genomic DNA preparations. The transcription and expression of the integrated CP gene was detected by Northern analysis and Western blots. Pathogen-derived resistance was demonstrated by inoculation the R1 progeny of the transformed lines with purified PVY-H. The efficiency of protection varied between different transgenic plants ranging from almost complete to no protection. Six CP expressing tobacco lines were resistant to challenge infection with PVY-H as indicated by attenuation or absence of symptom development associated with reduction or lack of detectable virus accumulation. Protection was also manifested upon inoculation with a different PVY strain. The level of resistance to PVY-H increased to almost 100% in four R2 lines indication that the obtained resistance is genetically stable. Data from Western blots showed that there is no correlation between the level of the expressed CP and the extent of protection. This suggests that the mechanism of the observed resistance is independent of the level of CP accumulation in the transgenic tobacco plants.