A report on byssinosis, an occupational respiratory disease of cotton, flax, and hemp workers, in the U.S. In the cotton industry, it occurs primarily among cardroom workers. Disabling byssinosis occurs among cotton workers irrespective of other environmental conditions such as air pollution, climate, and cigarette smoking. In this paper, data are presented on a group of cotton workers with respiratory disease from three southern states. The results suggest that it is urgently necessary to investigate the prevalence of byssinosis in the U.S. For 22 male cotton workers, respiratory symptoms, smoking habits, and occupational histories were recorded with a standard questionnaire. Three case histories of cardroom workers are recorded in detail. The Monday effect, respiratory distress only during the first day or two of the working week, of the dust has its objective correlate in acute pulmonary function changes developing during exposure to dust on Mondays. A discussion includes the history of textile workers, prevalence of chronic respiratory symptoms, and ventilatory capacities.