The study demonstrated that total RNA can be recovered from biological stains exposed to a variety of different environmental conditions in sufficient quantities to perform mRNA-based assays. On average, several hundred nanograms of total RNA were recovered from 50-ml-sized blood and saliva stains, 1 mg from a 50-ml semen stains, and nearly 70 mg from a whole vaginal swab. Messenger RNA was detectable in some samples stored at room temperature for at least 547 days. The environmental samples that were protected from direct rain impact exhibited housekeeping and tissue-specific mRNA recoverability up to 7 days for saliva and semen, 30 days for blood, and 180 days for the vaginal swab. Rain had a detrimental effect on the recoverability of specific transcripts for blood (3 days), saliva (1 day), semen (7 days), and vaginal secretions (3 days). The semen marker PRM2 was not detectable after 1 day. The persistence and stability of RNA within each type of body fluid stain were determined by quantitation of total RNA and reverse transcriptase-polymerase chain reaction, using eight different mRNA transcripts from selected housekeeping and tissue-specific genes. The description of material and methods addresses the body fluid samples RNA isolation, DNase treatment, RNA quantitation, cDNA synthesis, polymerase chain reaction, and gel electrophoresis. 3 tables, 4 figures, and 25 references