The 6-minute walk test (6MWT) is commonly used to measure walking ability. The purpose of this study was to determine the test-retest reliability and concurrent and construct validity of the 6MWT in patients who were actively undergoing inpatient rehabilitation poststroke. Thirty-seven patients undergoing inpatient rehabilitation after a stroke participated; mean age was 66.3 years and mean time since stroke was 33.7 days. Patients underwent two 6MWT trials with 1-3 days between trials. Additional outcome measures taken were gait speed and the Functional Independence Measure (FIM). The 6MWT exhibited high test-retest reliability; ICC(2,1) 0.973 (95% CI=0.925-0.988) and a minimal detectable change (MDC(90)) of 54.1 m. The 6MWT was strongly to moderately correlated with gait speed (r=0.89), locomotion (walk) FIM (r=0.69), and motor FIM (r=0.52). The 6MWT is a clinically useful measure of walking ability poststroke. It is reliable and is related to other measures of walking ability and function that are commonly used during rehabilitation after stroke.