Improved processing of cotton requires measurement of the trash in the cotton before and after cleaning at the gin. Cameras are currently used in some gins to measure trash levels. This study ascertained the relationships between standard laboratory tests (Shirley Analyser for lint and Fractionation for seed cotton) and marketing assessments of trash (High Volume Instrument) and mesurements by a new, strobe-type camera. About 1,000 samples each of seed cotton and lint representing the full range of trash levels expected in both spindle-harvested and stripper-harvested cottons were evaluated. Laboratory trash levels ranged from 2 to 36% for seed cotton and from 1 to 14% for lint. Significant regression equations accounted for 76% of the variations in the Shirley Analyser data for lint and 92% for seed cotton fractionation. Similar correlations were found for HVI trash and manual leaf grade.