Procedures are described for the preparation of a protein-free medium (ISFM) for the cultivation of an insect cell line (Spodoptera frugiperda, Sf9) and propagation of native or recombinant baculovirus (Autographa californica). An emulsification technique is detailed for the preparation of a lipid supplement—a key indgredient in replacing serum. Cultures are grown in suspension in Erlenmeyer flasks. Using the proteinfree medium, cell growth and virus titers are similar to those achieved in 10% serum-supplemented medium.