The Veterans Aging Cohort Study (VACS) Index has previously been used to identify frail HIV-infected persons. However, data demonstrating the independent association between the VACS Index and baseline frailty status is lacking. Furthermore, the ability of the VACS Index to also reflect transitions in frailty status over time is unknown. We used data from the Study to Understand the Natural History of HIV and AIDS in the Era of Effective Therapy (SUN Study) to determine independent association of baseline frailty status with the VACS Index. We also evaluated VACS Index changes with frailty status transitions over time. We included 303 participants (median age 48 years, 76% men, 57% non-Hispanic white, 91% with plasma HIV RNA <400 copies/ml, and median CD4+ cell count 595 cells/ml) with baseline and follow-up frailty assessments and used the Fried's criteria to define frailty status. There were 184 (61%) nonfrail, 112 (37%) prefrail, and seven (2%) frail participants at baseline. Prefrail/frail participants had significantly higher median VACS Index scores compared with nonfrail participants (18 versus 10, p<0.001). In multivariable analysis, prefrailty/frailty was independently associated with a higher VACS Index score (odds ratio 1.025, p=0.019). After a median follow-up of 12 months, participants who remained prefrail/frail compared to those who remained nonfrail continued to have higher median VACS Index scores. The VACS Index score did not significantly change with transitions in frailty status over time. Our study highlights the potential utility of the VACS Index in frailty assessment within the clinical setting.