The validation studies were performed according to the DNA Advisory Board's Quality Assurance Standards. The authors' descriptions of materials and methods addresses the extraction and quantitation of DNA, amplification, analysis of the amplified products, and contamination and environmental insult analysis. The presentation and discussion of the validation findings focuses on the development of the multiplex system, the generation of the allelic ladder, the precision of allele sizing and reproducibility, minimum sensitivity, stutter studies, internal control for PCR, the male-female mixture study, the two-male mixture study, female DNA, nonhuman studies, interlaboratory concordance study, contamination and environmental insult analysis, and nonprobative samples. The validation studies concluded that the Y-PLEXtm 12 system does reliably perform simultaneous amplification and analysis for the 11 Y-STR loci recommended by the SWGDAM, as well as the Amelogenin locus. Amelogenin provides results for gender identification and serves as an internal control for PCR. Amelogenin did not adversely affect the amplification of the Y-STR's. The system's sensitivity was sufficient to obtain a complete profile from as little as 0.1 ng of male DNA. 7 figures, 6 tables, and 35 references