The effect of solvent extraction on the mutagenicity of ambient airborne particles was evaluated. Airborne particles were collected with 8 by 10 inch high purity glass microfiber filters. These were extracted with acetone (67641), benzene (71432), cyclohexane (110827), dichloromethane (1300216), methanol (67561), acetone plus dichloromethane, and a mixture of benzene, cyclohexane, and methanol. The extracts were tested for mutagenic activity with the Ames Salmonella assay system using TA98 and TA100 strains. Samples extracted with acetone gave the highest mutagenic response. In additional experiments, sequential extraction of samples with 150 milliliters (ml) acetone, followed by 150ml dichloromethane and combination extraction with 150ml acetone plus 150ml dichloromethane were evaluated. Filters containing 150 milligrams (mg) of particles were extracted with 50 to 400ml of acetone and tested for mutagenicity as before. Sequential extraction with acetone followed by dichloromethane gave higher mutagenic response than extraction with acetone alone or acetone/dichloromethane. Extraction of the 150mg samples with varying amounts of acetone showed gradual increases in mutagenic activity up to 150ml of acetone. No further increase in mutagenic response was observed with increased solvent. The authors conclude that acetone is the most effective solvent for extraction of mutagens from airborne particles. Maximum recovery is obtained with a 1 to 1 ratio, ml to mg, or solvent to particles.