The environmental impact of the field release of transgenic European plums (Prunus domestica L.) carrying the coat protein (CP) gene of Plum pox virus (PPV) was assessed in Valencia over an eight-year experimental period. The obtained results are reviewed and discussed in this manuscript. The molecular variability of PPV populations present in transgenic vs. non-transgenic plums was compared, and total numbers and species of visitor aphids (PPV transmission vectors) and other arthropods that were found on transgenic and conventional plums were estimated. Additionally, the possibility of recombination between the transcripts derived from the transgene and the infecting viral RNA was tested. Five different P. domestica transgenic lines (the PPV-resistant C5 ‘HoneySweet’ line and the PPV-susceptible C4, C6, PT-6 and PT-23 lines) and non-transgenic P. domestica and P. salicina Lind trees, were tested. No differences in terms of diversity of PPV populations and numbers of aphids and other arthropod species that visited the trees were detected between transgenic and non-transgenic plums. No recombination between the transgene transcripts and the incoming viral RNA was detected over an eight-year period of exposure to natural PPV infection in the field. The overall data indicate that the growth of PPV-CP transgenic European plums under Mediterranean conditions does not represent an environmental risk, in terms of the parameters studied, beyond the cultivation of conventional plum trees.