Two Y-chromosome short tandem repeat (STR) multiplex polymerase chain reaction (PCR) assays were used to generate haplotypes for 19 single copy and 3 multi-copy Y-STRs. A total of 27 PCR products were examined in each sample using the following loci: DYS19, DYS385 a/b, DYS388, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS426, DYS437, DYS438, DYS439, DYS447, DYS448, DYS450, DYS456, DYS458, DYS460, DYS464 a/b/c/d, H4, and YCAII a/b. The first multiplex is the Y-STR 20plex previously described by Butler et al. [Forensic Sci. Int. 129 (2002) 10]. The second multiplex is a novel Y-STR 11plex and includes DYS385 a/b, DYS447, DYS448 and the new markers DYS450, DYS456, DYS458, and DYS464 a/b/c/d. These two multiplexes were tested on 647 males from three United States population sample sets: 260 African Americans, 244 Caucasians, and 143 Hispanics. Haplotype comparisons between common loci included in the 20plex and 11plex assays as well as commercially available kits found excellent agreement across a sampling of the population samples. The multi-copy loci DYS464, DYS385, and YCAII were the most polymorphic followed by the following single copy Y-STRs: DYS458, DYS390, DYS447, DYS389II, DYS448, and DYS456. Samples containing the most common type in the European database could be well resolved with additional markers beyond the minimal haplotype loci.