Veterinary growth promoters are widely used throughout the United States in livestock production. In beef production, steroid hormones are administered to an estimated 90% of cattle. These include the synthetic steroids trenbolone acetate and melengestrol acetate, as well 17ß-estradiol. Given the endocrine-modulating activity of steroid growth promoters, a sensitive and reliable analytical method is needed to detect trenbolone, melengestrol acetate, estradiol and related residues in environmental matrices. We have developed a method that incorporates solid phase extraction (SPE) and liquid chromatography-tandem mass spectrometry for he simultaneous determination of trendione, trenbolone, melengestrol acetate, estrone, and estradiol in airborne particulate matter samples. Sample preparation involved liquid-solid extraction followed by cleanup with SPE cartridges. Analytes were separated using reversed-phase liquid chromatography. Utilizing a fast gradient, analysis time was under 11 minutes, but did not provide complete isomeric separation of 17ß-trenbolone and 17a-trenbolone, or 17ß-estradiol and 17a-estradiol. Column effluent underwent atmospheric-pressure chemical ionization (APCI) followed by detection using a triple-quadrupole mass spectrometer in SRM mode. The lower limit of quantitation (LLOQ) was =0.55 ng/filter for all compounds. Recoveries ranged from 93%-116%, and coefficient of variation (CV) was =16.1% at all spiking levels.