OBJECTIVE: To evaluate the psychometric characteristics of the Acute Bronchitis Symptom Severity Scale (ABSS). METHODS: The ABSS is a seven-question, bronchitis specific, instrument. Responses are measured on a scale of 0-4. The total score is calculated as the mean of the seven responses with higher scores indicating greater distress. The ABSS was pilot tested as a part of a US-based prospective, naturalistic study to patients with acute exacerbation of chronic bronchitis at the pre-treatment visit, each day of the first five days of therapy with any antimicrobial agent, and at the test-of-cure visit (TOC, 18-21 days post therapy). Item and total scale performance, internal consistency (Cronbach's alpha), construct validity (correlation with St. George's Respiratory Questionnaire or SGRQ subscale), and responsiveness to change over time (based on clinician evaluation and patient's perceived treatment efficacy) were examined. RESULTS: 27 patients were enrolled at four study sites in the US. Mean age was 57.4 (+14.5) years; 74% were female. No floor or ceiling effects were seen. Consistent with an improvement in acute bronchitis symptoms over time, mean item and total score values declined from baseline to TOC. Cronbach's alpha at each time point ranged from 0.70 to 0.88, exceeding the reliability guideline of 0.70 for a new measure. At TOC, the correlation between the ABSS total score and SGRQ activity subscale score was strong (0.60). The 18 patients considered clinically cured or improved at Day 5 reported a mean ABSS score change, from baseline, of -0.90. Patients who considered the treatment moderately effective at Day 5 (n=11) reported an average change score of -0.87, while those who considered the treatment very effective (n=3) improved by a score of -1.50. CONCLUSIONS: Preliminary results from this pilot test with US-based patients suggest the instrument is valid, reliable, and sensitive to change over time.