OBJECTIVE:The objective of this study was to investigate the psychometric properties of the Modified Iowa Level of Assistance scale in hospitalized older adults in subacute care. DESIGN:A cohort, measurement-focused study. PARTICIPANTS AND SETTING:Fifty-eight older adults, aged 65 years and older, were recruited from a subacute rehabilitation hospital. METHODS:Inter-rater reliability was established by having two physiotherapists independently assess each participant within 24-h of each other. Construct validity was established using "known-groups" validity, while concurrent validity was also examined by correlating modified Iowa Level of Assistance scores with the Elderly Mobility Scale. Responsiveness was assessed by examining the difference in modified Iowa Level of Assistance scores from admission to discharge. RESULTS:The mean age of participants was 82.8 years (SD 7.5; range 68-97). The modified Iowa Level of Assistance scale was found to be reliable, valid, and responsive in this sample of hospitalized older adults. It had excellent inter-rater reliability (intraclass correlation coefficient [2,1] 0.96; 95% confidence intervals (CI) 0.93, 0.98) and no systematic differences across the range of scores. The scale displayed a mean difference between two known groups of 11.4 points and correlated significantly and negatively with the Elderly Mobility Scale (Spearman's rho - 0.90). The modified Iowa Level of Assistance score also changed significantly over the course of the hospital admission with an effect size of 1.2. CONCLUSIONS:The modified Iowa Level of Assistance scale is a valid measure with excellent inter-rater reliability in hospitalized older adults. It is responsive to functional change during hospital admission and may be useful for routine outcome assessment for hospitalized older adults in subacute care. Implications for Rehabilitation The mILOA scale is a valid, reliable, and responsive outcome measure that can be used to quantify the gait and mobility impairments in hospitalized older adults in subacute care. For optimal reliability and responsiveness, consistent administration of the mILOA scale will be required particularly for higher level mobility tasks such as negotiating a step.