Immunosenescence is an age-related reduction of immune system activity that can be associated with frailty. This study aimed to compare cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivations (based on viremias) between young and elderly women who had a chronic CMV and/or EBV infection (i.e., an IgG+ serostatus) without an acute infection (i.e., an IgM- serostatus), and among the elderly group categorized according to frailty status. DNA was extracted from plasma using standard protocols and serostatus was determined by enzyme-linked immunosorbent assay. Quantitative real-time polymerase chain reaction analyses for CMV and EBV were carried out and viral loads were determined. Among elderly women (n = 71), 59% were positive for CMV, in contrast to only 8% of young women (n = 73). Elderly women classified as frail, pre-frail, and non-frail presented 82%, 56%, and 48% positivity for CMV, respectively. Frequency and viral load were significantly higher in the elderly group vs. the young group (p < 0.0001 and p = 0.01, respectively) and in elderly with frailty vs. those without frailty (p = 0.007 and p = 0.03, respectively). The frequency of CMV reactivation presented odds ratios of 11.77 for aging and 6.13 for frailty, and relative risks of 5.39 for aging and 1.93 for frailty. EBV was detected in 30% of the elderly women and 15% of the young women (p = 0.04); however, the viral load did not significantly differ between the two age groups. The frequency of EBV reactivation presented odds ratios of 2.36 for aging and 2.90 for frailty, and relative risks of 1.96 for aging and 2.12 for frailty. However, no difference in EBV viral load among the frailty status subgroups was found. In conclusion, the frequency of CMV reactivation was associated with aging and ongoing frailty, whereas the frequency of EBV reactivation was associated only with aging.