Emerging data suggest that HIV disease and its treatment affect the aging process. Accurate and reliable measures of functional status are needed to investigate this further.A pilot study in groups of younger and older HIV-infected adults using objective measures of function.Evaluations included neuropsychological testing, grip strength, balance assessed by the Wii Balance Board, and actigraphy. Surveys were used for depression, fatigue, loneliness, self-reported activity level, and sexual function. Two-samplet test or Wilcoxon rank sum tests were used for continuous variables and exact chi-square tests were used for comparison between groups.Twenty-one participants were 20 to 40 years old (younger; mean age, 31.5), and 20 were more than 50 years old (older; mean age, 56.5). There was no difference between groups for depression, fatigue, or loneliness. Overall, there was a trend to lower scores in the older age group for neuropsychologicalz score (P = .11) and for verbal learning (P = .09). Functioning in the memory domain was significantly lower in older subjects (P = .007). There was no difference in executive function, speed of processing, memory, motor skills, or total activity. Gender differences in sexual function were observed. Four older and 3 younger participants met the definition of frailty. Total activity by actigraphy did not correlate well with self-reported activity.Objective tests were well accepted and feasible to perform, although not all are suitable for widespread clinical or research use. Objective measurements of activity did not correlate well with patient self-report, which has implications for future studies in this area.