This study explored the utility of sputum colour in clinically stable patients with bronchiectasis. Interpretation of sputum colour between the doctor and the patient was reliable (intraclass correlation coefficient 0.83 (95% confidence interval 0.76-0.89). Sputum colour predicted bacterial colonisation (5% in mucoid sputum; 43.5% in mucopurulent sputum; 86.4% in purulent sputum; p<0.0001). On multivariate logistic regression analysis, independent factors associated with purulent sputum were bacterial colonisation, varicose or cystic bronchiectasis, forced expiratory volume in 1 s <80% predicted and diagnosis of bronchiectasis aged <45 yrs.