Abstract: A human lipid-associated plasma protein has been produced in vivo in larvae of the Sphingid insect tobacco hornworm, Manduca sexta. The gene for the protein was introduced by recombinant Baculovirus into the body cavity of the larvae, which is a semi-permissive host for the virus. After the larvae had grown further, the hemolymph of the larvae was recovered. The yield of protein produced was much better than could be achieved for the same gene expressed in insect cell culture and a much higher percentage of the protein produced in vivo was associated in lipid particles as compared to the cell culture system. The desired biological activity of the lipid-associated protein was achieved by the in vivo produced protein but not by the protein produced by insect cells in culture.