Stroke remains a leading cause of disability, with those affected usually experiencing long-term motor deficits. The National Institutes of Health Stroke Scale (NIHSS) is commonly used to measure acute neurological status, but recently is being deployed in at least 29 chronic stroke trials as a secondary UE motor outcome despite a lack of evidence surrounding its validity in chronic stroke. The purpose of this secondary, retrospective analysis of randomized controlled, multicenter, trial data was to (a) determine the NIHSS’s association with the Stroke Impact Scale (SIS), a poststroke health status measurement, the upper extremity Fugl Meyer (UEFM) and the Arm Motor Ability Test (AMAT), measures of upper extremity (UE) impairment and functional limitation and (b) determine the NIHSS’s sensitivity to UE motor change over time. There was no association between total NIHSS scores and SIS physical dimension, overall perception of recovery, activity of daily living scores (P = -.036, P = .782; P = -.039, P = .640; P = -.054, P 5.520, respectively) or functional limitation (P; = –0.141; P; = 0.089). NIHSS and UE impairment associations were significant (P; = –0.204; P; = 0.014) but explained less than 4% of the variance among UEFM scores. Subjects scoring a “zero” on the NIHSS exhibited discernible UE motor deficits and varied scores on the UEFM, AMAT, and SIS. A statistically significant sensitivity to change was found for the UEFM (χ2(3) = 10.783, p = 0.013), but not for NIHSS (X2(3) = 1.250, p = 0.741) or either AMAT functional ability or quality of movement scores (χ2(3) = 3.953, p = 0.267; χ2(3) = 4.199, p = 0.241, respectively). There was a significant weak, negative correlation between the NIHSS and UEFM (rs(47) = -.325, p = .026), but nonsignificant weak, negative correlations between the NIHSS and either AMAT scores (rs(47) = -.051, p = .740; rs(47) = -.103, p = .489, respectively). While being increasingly used in postacute trials, the NIHSS’s weak correlation with measures of motor impairment, functional limitation, and health status measurements as well as its insensitivity to change suggest that its use be reserved to acute bedside status. Its utility as a predictor of real world UE motor outcomes has been purported and is currently under investigation as a next step.