TRANSPATH is an information system on gene-regulatory pathways, and an extension module to the TRANSFAC database system (Wingender et al., Nucleic Acids Res., 28, 316-319, 2000). It focuses on pathways involved in the regulation of transcription factors in different species, mainly human, mouse and rat. Elements of the relevant signal transduction pathways like complexes, signaling molecules, and their states are stored together with information about their interaction in an object-oriented database. The database interface provides clickable maps and automatically generated pathway cascades as additional ways to explore the data. All information is validated with references to the original publications. Also, references to other databases are provided (TRANSFAC, SWISS-PROT, EMBL, PubMed and others).