A cross-sectional study of respiratory function was performed in 50 sisal textile workers in 1972. Twenty of the 50 sisal workers still employed in the sisal mill were reexamined 19 years later. At the time of the initial study there were higher prevalences of all chronic respiratory symptoms in sisal compared with control workers. By the time of the follow-up study a significant increase had occurred in almost all chronic respiratory symptoms among the 20 sisal workers. At the time of the initial study there were similar and statistically significant across-shift reductions of forced vital capacity (FVC) and the 1-s forced expiratory volume (FEV1) on Monday and the following Thursday of the work week. Across-shift reductions in FVC and FEV1 in the 20 sisal workers at the follow-up study were larger than at the first measurement. Two sisal workers out of 20 (10.0%) had a positive skin test reaction to an extract sisal; both related symptoms of occupational asthma. In two sisal workers (10.0%) increased IgE was measured; one of these had symptoms of occupational asthma. Our data suggest that exposure to sisal dust in the textile industry may, in some workers, cause the development of respiratory difficulties. Immunological testing may be of value in identifying such workers at risk for occupational asthma.