MDevTrDb is a searchable database for the mammalian transcriptome and epigenome during development. The database provides transcriptome information at three levels- gene, promoter and transcript while the epigenome information is at promoter level only. All information available is derived from ChIP-seq and mRNA-seq experimental studies. MdevTrDb promoter and transcript annotation are based on the integrated inventory of records from RefSeq genes, Ensembl genes, Vega genes, UCSC known genes, Aceview, Tromer Transcriptome database, Exoniphy genes, SGP genes, N-Scan and Genscan gene predictions. The database contains the active promoters and their corresponding transcripts for each protein coding and non-coding genes at various developmental stages. The transcript expression presented is based on the calculations by IsoformEX program and the epigenetic mark and mRNA expression profiles could be visualized on the linked UCSC genome browser. Currently the database contains information for the postnatal development of cerebellum in mouse and as more experimental data is available on different developmental programs in mouse and humans, the database will be updated. Our long term goal is to provide a comprehensive database for the transcriptome and epigenome of various developing tissues and organs in mammals.