A respiratory symptoms questionnaire was completed for 4656 volunteers employed in 31 textile factories engaged in spinning or weaving manmade fibre or cotton of various qualities. Sets of airborne dust and bacteria samples were collected in workzones and personal breathing zones in the workrooms where the volunteers were employed. A total of 182 people indicated experiencing byssinotic symptoms, mainly in opening and carding rooms or in spinning and winding rooms where medium to coarse cotton was being processed. This represents a significant decline in the prevalence of byssinotic symptoms over the years, due possibly to lower concentrations of airborne contaminants, especially of bacteria, as cleaner raw materials are being used. According to a multiple, logistic regression model, the prevalence of byssinotic symptoms was found to be statistically significantly related to years worked in the cotton industry, exposure to dust, quality of cotton used, workroom of employment, ethnic origin, and smoking habits. Symptoms of chronic bronchitis were found to be significantly related to smoking habit and to factors connected with occupation, such as exposure to dust, workroom, and the quality of fibre processed.