Genetic resistance provides efficient control of crop diseases but is limited by pathogen counteradaptation. The durability of the pvr23 allele, conferring resistance to Potato virus Y (PVY), was demonstrated to depend on the plant genetic background. In order to identify genetic factors affecting the durability of the pvr23 resistance, QTL mapping was performed using doubled-haploid (DH) lines issued from the F1 between two Capsicum annuum lines: ‘Perennial’ carrying pvr23 in a partially resistant background and ‘Yolo Wonder’ carrying the susceptible pvr2+ allele in a susceptible background. 350 DH lines were genotyped with 234 markers and the linkage map was established. The 156 DH lines carrying the pvr23 allele but segregating for the genetic background were evaluated for two traits: the breakdown frequency of pvr23 (following inoculation with a PVY clone nonpathogenic (avirulent) towards pvr23) and the PVY accumulation (following inoculation with a mutant of the previous PVY clone carrying a single mutation conferring pathogenicity towards pvr23). Genotypic variance was highly significant for the two traits with heritabilities of 0.76 and 0.47. One major QTL, explaining 29% of the variance of pvr23 breakdown frequency was identified on chromosome 3 and two QTLs, explaining 25% and 9% of PVY accumulation variation, were identified on chromosomes 3 and 6, respectively. Interestingly, the major QTL for the 2 traits mapped to the same region of chromosome 3. A putative pleiotropic effect affecting simultaneously the two traits, the underlying mechanism and the perspective in breeding for resistance durability will be discussed.