The mutagenic activities of ambient airborne particles were assessed and compared in the Ames Salmonella microsome assay system and the arabinose resistance Salmonella assay system after acetone extraction by shaking, soxhletion, or sonication. Collection of the airborne particles was done during the summer of 1982 using a high volume sampler with glass microfiber filters at a height of 10 meters above ground. Sampling proceeded continuously over a period of 48 hours at a flow rate of 60 cubic feet per minute. Each extraction method was tested using several different duration times to determine optimum duration time for extraction. The three methods were then compared for extraction efficiency using the optimum duration time. Tester strains used were (TA-98) and (TA- 100) for the Ames Salmonella assay and (SV-50) for the arabinose resistance test. The mutagenic activity of extracted airborne particles was greatest at 4 hours for shaking, 1 hour for soxhlet extraction, and 1/8 of a minute for sonication. The results of the Salmonella assay system and the arabinose resistance test were comparable with regard to extraction time, and similar responses were observed with and without microsomal activation. There were no significant differences in the mutagenic responses of the three strains used. The order of mutagenic activity of extracts from highest to lowest at optimum extraction time was sonication, shaking, and soxhletion. The authors conclude that acetone extraction by sonication is the best method for extraction of mutagens from airborne particles.