In summary, this cross sectional study has documented reduced lung function associatedwith workplace e xposure to cotton dust. Operatives with byssinosis, chronic bronchitis, and work related wheeze had significantly impaired lung function compared with operatives without these symptoms. Women operatives and those working with man made fibres or blends seemed to have less impairment of measured lung function. Regression analysis identified smoking, however, as the most significant single determinant of a reduced FEV, and FVC although the duration of cotton exposure in the waste room did enter into the prediction for loss in FEV, and FVC. The likely situation is that smoking and dust exposure interact in a complicated manner to augment the loss in lung volume.