Bacterial tyrosine-kinases share no resemblance with their eukaryotic counterparts and they have been unified in a new protein family named BY-kinases. These enzymes have been shown to control several biological functions in the bacterial cells. In recent years biochemical studies, sequence analyses and structure resolutions allowed the deciphering of a common signature. However, BY-kinase sequence annotations in primary databases remain incomplete. This prompted us to develop a specialized database of computer-annotated BY-kinase sequences: the Bacterial protein tyrosine-kinase database (BYKdb). BY-kinase sequences are first identified, thanks to a workflow developed in a previous work. A second workflow annotates the UniProtKB entries in order to provide the BYKdb entries. The database can be accessed through a web interface that allows static and dynamic queries and offers integrated sequence analysis tools. BYKdb can be found at http://bykdb.ibcp.fr.