Brooks D, Davis AM, Naglie G. Validity of 3 physical performance measures in inpatient geriatric rehabilitation. To evaluate the construct validity and the responsiveness of 3 measures of physical performance measures as outcome measures for frail older persons. Pre-post design with measures at admission and discharge. Three inpatient geriatric rehabilitation programs. Fifty-two subjects (35 women, 17 men; age, 80±8y). Not applicable. Physical performance measures were Timed Up & Go (TUG) test, two-minute walk test (2MWT), and functional reach. Functional status was measured with the FIM instrument and the Modified Barthel Index. The TUG and 2MWT scores differed significantly in groups of patients using different ambulatory aids (P=.006), whereas no such difference was observed for the functional reach (P=.40). The correlations between the TUG test and FIM and between the 2MWT and FIM were –.59 and .59 (P<.001), respectively, at admission, and –.42 and .47 (P≤.04), respectively, at admission and discharge. The correlations between functional reach and the FIM were not significant (P≥.09). Standardized response means were 1.1 for the TUG, 0.7 for the 2MWT, and 0.5 for functional reach. The TUG test and 2MWT are valid and responsive outcome measures in older persons participating in geriatric rehabilitation. Functional reach was a moderately responsive outcome measure but did not consistently reflect ambulatory or functional status.