The present invention provides the complete nucleotide sequence of a bovine adenovirus. The invention further provides bovine adenovirus vectors and expression systems which can be used, among other things, for insertion of foreign sequences, for provision of DNA control sequences including transcriptional and translational regulatory sequences, for diagnostic purposes to detect the presence of viral nucleic acids or proteins encoded by these regions in a subject or biological sample, for provision of immunogenic polypeptides or fragments thereof, for vaccines and for gene therapy. Cell lines comprising the vectors of the invention, and methods for making bovine adenovirus vectors are also provided.