Particularly troublesome are cases involving complainants who are not able to relate a complete history. Small numbers of spermatozoa on clothing may be due to some type of sexual activity or to an unrelated innocuous incident. Because the transfer of spermatozoa between items during machine washing has been theorized as a possible method of indirect deposition, the current study was conducted by Canada's Centre of Forensic Sciences to determine the likelihood of such transfer. A normal machine wash was simulated in three independent experiments. Pristine items of clothing were washed together with a pair of semen-stained panties. After washing, 162 random samples from nine unstained items were examined microscopically. Some spermatozoa were detected on all nine previously pristine items included in the washloads. Three to eight spermatozoa were identified in 16 percent of the samples. One or two spermatozoa were identified in a further 38 percent of the samples. The original semen-stained panties were also examined after washing. Although no visible staining or acid phosphatase activity was observed, significant numbers of spermatozoa were retained in the original stain areas. The analysis and interpretation of these findings is discussed with reference to current DNA methods. 5 references, 2 tables, and 1 figure