Bacterial artificial chromosome (BAC) vectors are increasingly used for generation of transgenic mice due to the relatively large size and the stability of their inserts compared to YACs. We have compared methods for purification and linearization of BACs, and describe an optimised protocol for preparation of high quality linear BAC DNA based on lambda terminase digestion, electroelution of linearized DNA together with simple preliminary multiplex PCR screening to detect transgenic mice. Linearized BAC DNA purified this way was successfully used for the development of transgenic mice containing 2-4 copies of the transgene.