A package dedicated to the object-oriented representation and analysis of microbiome census data in R. Phyloseq supports importing data from a variety of common formats, as well as many analysis techniques. These include calibration, filtering, subsetting, agglomeration, multi-table comparisons, diversity analysis, parallelized Fast UniFrac, ordination methods, and production of publication-quality graphics, all in a manner that is easy to document, share, and modify. It simplifies many of the common data management and preprocessing tasks required during analysis of phylogenetic sequencing data. The phyloseq package also provides a set of powerful analysis and graphics functions, building upon related packages available in R and Bioconductor. It includes or supports some of the most commonly-needed ecology and phylogenetic tools, including a consistent interface for calculating ecological distances and performing dimensional reduction.