Transformed Bm5 or Sf9 cells displaying green fluorescence were constructed by using Autographa californica nuclear polyhedrosis virus (AcNPV) immediate early gene(iel). Green fluorecent protein(gfp) gane was introduced under the control of the AcNPV iel promotor to yield expression plasmid pAcIE1-GEP. It was transfected into Sf9 or Bm5 cells and cell clones expressing GFP were selected by fluorescence microscopy. Genomic DNA from transformed cells was isolated and integration of AcNPV iel gene harboring gfp gene was confirmed by PCR using AcNPV iel gene-specific primers. The GFP was successfully expressed in the cytoplasm of insect cells transformed with pAcIE1-GFP and the expressed GFP was maintained during cell division. Furthermore, GFP expression by AcNPV iel promoter in transformed cells was not interfered with viral replication. This suggests that transformed cells displaying foreign gene product by using AcNPV iel promoter will be useful for the diverse applications of the insect cells.