Silkworm hemolymph when added at 5% (v/v) to medium increased the production of recombinant beta-galactosidase in Spodoptera frugipera/Autographa californica nuclear polyhedrosis virus (AcNPV) system by 4.5-fold. Silkworm hemolymph also increased the host cell longevity by two-fold. Viability of the host cell was maintained at a constant level for 6 days after baculovirus infection in the medium containing 5% silkworm hemolymph, while host cells began to die 3 days after infection in the medium without hemolymph.