A simple method for extracting mutagenic materials from airborne particles was described. Airborne particles collected by a high volume sampler on 8 by 10 inch high purity glass microfiber filters were soaked in 150 milliliters (ml) of acetone for 0.5 hours. The extract was filtered through Whatman number 2 filter paper. After rinsing with an additional 25ml acetone, the extract was evaporated to dryness. The residue was dissolved in dimethyl-sulfoxide and assayed for mutagenicity in the Ames/Salmonella assay utilizing strains (TA-98), (TA-100), and SV-50 with and without S9 liver mix from aroclor induced rats. Similar experiments were performed in which the particles were processed by shaking for 4 hours, soxhletion for 1 hour, or sonication for 1 minute with acetone for comparison purposes. Samples that had been soaked in acetone had the highest mutagenic activity, followed by those that had been sonicated, shaken, or soxhleted in that order. Experiments leading to optimization of the soaking procedure were described. The authors conclude that soaking with acetone for 0.5 hour is the simplest and most efficient procedure for extracting mutagenic substances from airborne particles.