Probably the most important forensic application of genetic fingerprinting will be in the identification of rapists. Conventional methods give results which are difficult to interpret because both vaginal fluid and semen have enzyme and blood group activity. However, Gill et al.demonstrated a technique of separating sperm from vaginal material, which allows the examination of sperm DNA in isolation. In this paper we describe: (i) The results of an independently organised blind trial (blind trials are an essential quality assurance prerequisite before any system can be considered for use in casework). (ii) The results of analyses of extracts from 100 semen-contaminated vaginal swabs from 5 volunteer donor couples. (iii) The potential of obtaining vaginal DNA fingerprints from penile swabs. (iv) A limited stability study of DNA in blood stains stored in humid conditions. (v) The isolation of DNA from buccal swabs which could be useful in those cases where blood cannot be obtained