Workers in the "non-textile" cotton industry breathe a dust which is similar to the dust in the cotton spinning and weaving or "textile" industry. This exposure prompts the question of byssinosis prevalence and other respiratory disease in the non-textile cotton industry. NIOSH has completed a cross-sectional medical and environmental study evaluating the prevalence of byssinosis in five segments of the non-textile cotton industry. A total of 92 non-textile cotton facilities were evaluated, including cotton gins, cotton classing offices, cottonseed oil mills, cotton compress-warehouses, and waste utilization plants. This paper presents the results of the measurements of cotton dust levels and particle size distributions in these segments. Average elutriated dust concentrations for individual plants ranged from 101 to 2050 micrograms per cubic meter of air (micrograms/m3) in 35 cotton gins, 81 to 376 micrograms/m3 in 13 classing offices, 502 to 2041 micrograms/m3 in 18 cottonseed oil mills, 39 to 831 micrograms/m3 in 13 compress-warehouses, and 237 to 3968 micrograms/m3 in 13 waste utilization facilities. Results tend to be lower than those reported in the literature for non-textile operations.