The important discovery of hypervariable minisatellite DNA [ 11 has provided the forensic scientist with a means of dis- criminating between individuals that is many orders of mag- nitude greater than a combination of all the techniques cur- rently in use in forensic science laboratories. Jeffreys [2] show- ed that the mean probability that all DNA fragments detected, by one probe 33.15, in individual A are also present in a ran- domly chosen individual B is < 3 x lo-”. Furthermore, minisatellite DNA has been shown to be stable in human blood and semen stains [3] and the DNA fingerprints obtained are unaffected by microbial contamination of the stains. This is because the probes for hypervariable minisatellite regions will not hybridise to DNA from bacteria or yeasts which are fre- quent contaminants of swabs and stains of body fluids. DNA fingerprinting, therefore, has several clear advantages over other techniques currently in use.