A recent report in the Perkin Elmer "Forensic Forum" bulletin described a modification to the previously published PM typing protocol, indicating that in order to obtain consistent and reliable PM and DQA1 typing results, disodium EDTA should be added to the post-amplification mixture before denaturation of the DNA fragments. The analysis and validation of this suggestion is described in this article. It explains the evaluation of this additional step when typing for PM alleles and concludes that the standard operating procedures currently enforced at the Palm Beach County Sheriff's Office and Indian River crime laboratories do not require the addition of disodium EDTA to the PM amplified products prior to the heat denaturation step. Further, depending on an individual laboratory's PM protocol, the recommendation by Perkin Elmer to add disodium EDTA to PM amplified products before typing has merit and should be carefully considered when determining laboratory PM typing protocols. 4 figures and 5 references