Co-infection with several viruses is often used to achieve simultaneous expression of several proteins. From co-infections involving several viruses, the ratio of proteins synthesized in individual cells can be very variable. This is disadvantageous where proteins are needed to interact to provide a maximum yield of a complex product. Multiple-gene-expression vectors offer an alternative to co-infections. They enable reproducible ratios of products to be provided in each infected cell. Until recently, multigene-expression vectors have only been developed to make two proteins simultaneously. Here, we describe the generation of a single recombinant baculovirus synthesising up to five foreign proteins with a fixed ratio comparable to the ratio during the synthesis of native proteins.