The Aphasia Rapid Test (ART) is a 26-point scale developed as a bedside assessment to rate aphasia severity in acute stroke patients in <3 min. We tested its inter-rater reproducibility, its sensitivity to detect changes from Day 1 to Day 8, and the predictive value of D8 ART scores on the 3-month aphasia outcome assessed with the Aphasia Handicap Score (AHS), a 0-5 "Rankin-like" score for aphasic disability. The reproducibility was tested in 91 aphasic patients within one week of stroke onset. The inter-rater concordance coefficient was 0.99 and the weighted Kappa value (κw) was 0.93. The sensitivity was tested in 70 aphasic patients by measuring changes in ART values between D1 and D8. Improvement occurred in 46 patients (66 %) and aggravation in three patients (4 %). In these patients, a logistic regression analysis showed that D8 ART was the only significant predictor of good (AHS 0-2) or poor (AHS 4-5) outcome. The ROC curves analyzes showed areas under the curve above 0.9 for good and poor outcome and revealed D8 ART best cut-off values of <12 for good and >21 for poor outcome, with more than 90 % sensitivity and 80 % specificity. The ART is a simple, rapid and reproducible language task, useful in monitoring early aphasic changes in acute stroke patients and highly predictive of the 3-month verbal communication outcome. It should be easy to adapt to other languages.