The diversity of the human microbiome is underexplored, as exemplified by a recent study that recovered thousands of new species. Segata and colleagues used a large-scale metagenomic-assembly approach to reconstruct bacterial and archaeal genomes from publicly available databases and newly obtained samples that span multiple populations, body sites, ages and lifestyles. The authors reconstructed more than 150,000 genomes and obtained 4,930 species-level genome bins (SGBs). They found that 3,796 of the SGBs (77%) did not contain genomes from sequenced isolates or publicly available metagenomic assemblies, thus greatly expanding the diversity of the human microbiome. They also report that non-Westernized populations harbour a large fraction of the newly discovered species. This new genome set provides a resource for future studies to further explore the phylogenetic and functional diversity of the human microbiome.