The polymerase chain reaction was applied to the analysis of DNA contained in archival paraffin wax embedded material. DNA suitable for the reaction was obtained from these tissues by simple extraction methods, without previous dewaxing of tissue sections. When compared with unfixed material, the reaction efficiency was compromised, so that an increased number of amplification cycles were required to produce equivalent amounts of amplified product. This in turn led to an increase in amplification artefacts, which can be minimised by a simple modification of the standard reaction. Amplification of relatively large DNA fragments was not always successful, and it seems prudent to bear this in mind when designing oligonucleotide primers which are to be used for the amplification of archival material. The efficiency of the procedure can be improved by dividing the amplification cycles into two parts: this reduces the amount of reagent needed, is relatively simple and inexpensive, and can be performed in one working day.