According to TWGDAM (Technical Working Group on DNA Analysis Methods) guideline 4.5, prior to implementing a new DNA analysis procedure or an existing DNA analysis procedure developed by another laboratory, the forensic laboratory must first demonstrate reliability of the procedure in-house. Seven phases were designed to validate use of the AmpFlSTR Profiler Plus PCR Amplification Kit as well as the PE Applied Biosystems 310 Genetic Analyzer. The seven phases of the validation study included the following evaluations: polymer, reproducibility, sensitivity, stutter, precision, mixtures, and nonprobative casework. The Profiler Plus Amplification Kit is a multiplex PCR reaction kit designed to amplify nine tetrameric repeat loci on nine separate chromosomes plus a homologous region of the Amelogenin gene on the X and Y chromosomes. The validation phases were completed at the Illinois State Police Research and Development Laboratory, Springfield, IL, and the Forensic Science Center, Chicago, IL. Once the validation studies were completed, the Science Center and the Laboratory completed an internal proficiency test and an external proficiency test. Tables, references