Baculoviruses have been used for many years as effective pest-control agents; however, their interest to molecular virologists stems from their exploitation as helper-independent viral expression vectors for the production of proteins in a eukaryotic environment. The pioneering work that led to the development of the system came from the laboratory of Max Summers at Texas A & M, USA. Since its inception, the system has been increasingly utilized to express a broad range of eukaryotic proteins (reviewed in ref. 1) and has been extensively modified (2), in particular by David Bishop and Bob Possee at the Institute of Virology and Environmental Microbiology, Oxford, UK. This work has led to the construction of single and multiple baculovirus expression vectors. Extensive reviews on the subject of baculoviruses are available (1,3-5), including a manual of methods specific for their use as expression systems (6). Chapters 26 - 28 aim to provide a practical account of baculoviruses as expression vectors, along with the experimental methodologies required to produce a baculovirus transfer vector containing the gene to be expressed, the generation and selection of a recombinant expressing this gene product, and the methods available for processing downstream the baculovirus-produced protein.