Many workers in the textile industry have respiratory symptoms that are related to their work environment. In this study we observed the dust level conditions of eleven textile industries of the North of Portugal. The dust levels determined were between 0.1 mg/m3 and 1.25 mg/m3, in many cases above the Portuguese standard levels of exposure (VLE). For these dust levels we found a prevalence of 23% of workers with respiratory symptoms with occupational characteristics in 10.8%, and 5.7% presenting byssinosis. Workers exposed to cotton fibres in spinning areas have the highest prevalence of symptoms, and reduction of the FEV1. These characteristics were related to dust levels and were higher in the initial phases of the spinning processes. We found no cases of byssinosis in workers exposed to synthetic fibres, or in workers from weaving areas. Smoking habits were related to the reduction of the FEV1, and severity of respiratory illness but not to the presence of byssinosis.