The vaginal microbiome of reproductive-age women was studied to understand its role in preventing urogenital diseases and maintaining health. Researchers analyzed the bacterial communities of 396 asymptomatic North American women from four ethnic groups (white, black, Hispanic, and Asian) using pyrosequencing of barcoded 16S rRNA genes. The communities were grouped into five types, with four dominated by Lactobacillus species and one containing more strictly anaerobic bacteria. These groups showed significant differences among ethnicities, with higher vaginal pH observed in Hispanic and black women compared to Asian and white women. Correlated phylotypes were found in all communities, and these patterns were associated with Nugent scores, used to diagnose bacterial vaginosis. The study highlights the importance of considering ethnic differences in vaginal microbiome composition for accurate disease diagnosis and risk assessment. The vaginal microbiota plays a key role in preventing urogenital diseases such as bacterial vaginosis, yeast infections, and HIV. Lactic acid-producing bacteria, particularly Lactobacillus species, are thought to protect the vaginal environment by lowering pH and producing bacteriostatic compounds. Recent molecular techniques have identified new taxa in the vaginal microbiota, but these methods are limited by cost and throughput. This study used a high-throughput pyrosequencing method to characterize the vaginal microbiome of 396 women, revealing five major community groups. These groups varied in species composition and pH, with group IV showing the highest diversity and pH. The study also identified correlations between community composition and Nugent scores, suggesting that these patterns may reflect ecological interactions. The study found that the vaginal microbiome varies significantly among ethnic groups, with Hispanic and black women having higher pH values and different community compositions. These differences highlight the need for a more refined understanding of normal vaginal microbiota and the importance of considering individual variations in risk assessment and disease diagnosis. The results suggest that communities not dominated by Lactobacillus are common in Hispanic and black women and may be considered normal. The study also emphasizes the importance of considering the dynamic equilibrium of vaginal microbial communities and the role of interspecies interactions in community stability and resilience. The findings have implications for personalized medicine in women's reproductive health, where individual differences in vaginal microbiomes should be taken into account for risk assessment and treatment.The vaginal microbiome of reproductive-age women was studied to understand its role in preventing urogenital diseases and maintaining health. Researchers analyzed the bacterial communities of 396 asymptomatic North American women from four ethnic groups (white, black, Hispanic, and Asian) using pyrosequencing of barcoded 16S rRNA genes. The communities were grouped into five types, with four dominated by Lactobacillus species and one containing more strictly anaerobic bacteria. These groups showed significant differences among ethnicities, with higher vaginal pH observed in Hispanic and black women compared to Asian and white women. Correlated phylotypes were found in all communities, and these patterns were associated with Nugent scores, used to diagnose bacterial vaginosis. The study highlights the importance of considering ethnic differences in vaginal microbiome composition for accurate disease diagnosis and risk assessment. The vaginal microbiota plays a key role in preventing urogenital diseases such as bacterial vaginosis, yeast infections, and HIV. Lactic acid-producing bacteria, particularly Lactobacillus species, are thought to protect the vaginal environment by lowering pH and producing bacteriostatic compounds. Recent molecular techniques have identified new taxa in the vaginal microbiota, but these methods are limited by cost and throughput. This study used a high-throughput pyrosequencing method to characterize the vaginal microbiome of 396 women, revealing five major community groups. These groups varied in species composition and pH, with group IV showing the highest diversity and pH. The study also identified correlations between community composition and Nugent scores, suggesting that these patterns may reflect ecological interactions. The study found that the vaginal microbiome varies significantly among ethnic groups, with Hispanic and black women having higher pH values and different community compositions. These differences highlight the need for a more refined understanding of normal vaginal microbiota and the importance of considering individual variations in risk assessment and disease diagnosis. The results suggest that communities not dominated by Lactobacillus are common in Hispanic and black women and may be considered normal. The study also emphasizes the importance of considering the dynamic equilibrium of vaginal microbial communities and the role of interspecies interactions in community stability and resilience. The findings have implications for personalized medicine in women's reproductive health, where individual differences in vaginal microbiomes should be taken into account for risk assessment and treatment.