High-density tiling microarray and RNA sequencing technologies were used to analyze the transcriptome of Porphyromonas gingivalis. The compiled P. gingivalis transcriptome were based on total RNA samples isolated from three different laboratory culturing conditions and the strand-specific transcription profiles generated covered the entire genome including both protein coding and non-coding regions. The transcription profiles revealed various operon structures, 5' and 3' end untranslated regions (UTRs), differential expression patterns, and several not-yet annotated transcripts within intergenic and antisense regions. Further transcriptome analysis identified the majority of the genes to be expressed within operons and most 5' and 3' ends to be protruding UTRs of which several 3’ UTRs were extended to overlap genes encoded on the opposite/antisense strand. Extensive antisense RNAs were identified opposite to most of insertion sequence (IS) elements. With the growing realization that non-coding RNAs play important biological functions, the comprehensive transcriptome profiles compiled in this study are of great value for the further understanding of gene regulation and virulence mechanism in this periodontal pathogen. The transcriptome profiles can be viewed at and downloaded from the 'Microbial Transcriptome Database' web site http://bioinformatics.forsyth.org/mtd. 3 total RNA samples from growing P. gingivalis strain W83 under different media conditions subjected to RNA-Seq.