Although cough and sputum production may impact patients' well being and functioning in COPD and chronic bronchitis, there is no validated instrument for cough and sputum symptoms and their impact on patients' daily activities. To fill that gap, we developed and validated a specific, multilingual Cough and Sputum Assessment Questionnaire (CASA-Q) that evaluates clinical symptoms and their impact on patients with COPD or chronic bronchitis. In a three-country validation study (n=671), there was adequate internal consistency (Cronbach's alphas, 0.80-0.91) and test-retest reliability (correlation coefficients>0.70) for the CASA-Q. The cough impact and sputum impact domains correlated with the SGRQ impact domain and SGRQ total score, as did the cough impact domain with the SF-36 social functioning domain. The cough symptom and sputum symptom domains correlated with sputum wet weight (p<0.05; r=-0.56), but not with cough recordings. The mean CASA-Q cough symptom and sputum symptom domain scores indicated responsiveness towards both worse and improved symptoms, whereas the impact domains scored already in the upper third of the scale range, indicating the need for further improvement of its properties. Differences in the CASA-Q domain scores by smoking status (current vs. former smokers) were highest for cough symptoms and lowest for sputum impact. These data indicate that the CASA-Q may be a useful measure of cough and sputum production, and their impact in patients with COPD and/or chronic bronchitis. Further validation will need to assess the responsiveness of the CASA-Q to changes in symptoms.