Insect cells ( Spodoptera frugiperda) have been cultured in a stationary bed reactor, packed with a fibrous polyester carrier. When the bioreactor was perfused with serum-supplemented medium, a cell density of 6 × 10 6 cells ml −1 packed carrier was reached. Scanning electron microscopy investigations have shown that the insect cells grew along the three-dimensionally oriented fibers of the Fibra-cel carrier. After infection of the logarithmically growing cells with a recombinant baculovirus ( Autographa californica) containing the gene coding for β-galactosidase, the medium in the bioreactor was changed to serum-free medium. At day 13 postinfection (p.i.), a β-glactosidase level of 320 μg ml −1 and, at day 17 p.i., a virus titer of 2.1 × 10 8 TCID 50 units ml −1 (day 17 p.i.) were reached. In another bioreactor, operated in a similar way but with serum-containing medium, a β-galactosidase concentration of 360 μg ml −1 and a virus titer of 2.3 × 10 8 TCID 50 units ml −1 were obtained. These results indicate the potential use of this production system for the production of recombinant protein and baculovirus in insect cells.