The mtDNA composition of two Muslim sects from the northern Indian province of Uttar Pradesh, the Sunni and Shia, have been delineated using sequence information from hypervariable regions 1 and 2 (HVI and HVII, respectively) as well as coding region polymorphisms. A comparison of this data to that from Middle Eastern, Central Asian, North East African, and other Indian groups reveals that, at the mtDNA haplogroup level, both of these Indo-Sunni and Indo-Shia populations are more similar to each other and other Indian groups than to those from the other regions. In addition, these two Muslim sects exhibit a conspicuous absence of West Asian mtDNA haplogroups suggesting that their maternal lineages are of Indian origin. Furthermore, it is noteworthy that the maternal lineage data indicates differences between the Sunni and Shia collections of Uttar Pradesh with respect to the relative distributions of Indian-specific M sub-haplogroups (Indo Shia > Indo Sunni) and the R haplogroup (Indo Sunni > Indo Shia), a disparity that does not appear to be related to social status or geographic regions within India. Finally, the mtDNA data integrated with the Y-chromosome results from an earlier study, which indicated a major Indian genetic (Y-chromosomal) contribution as well, suggests a scenario of Hindu to Islamic conversion in these two populations. However, given the substantial level of the African/Middle Eastern YAP lineage in the Indo-Shia versus its absence in the Indo-Sunni, it is likely that this conversion was somewhat gender biased in favor of females in the Indo-Shia. Am J Phys Anthropol, 2007. © 2007 Wiley-Liss, Inc.