This report describes the first production of recombinant forms of Heliothis (Helicoverpa) armigera entomopoxvirus (HaEPV). These HaEPVs are engineered at either the spheroidin or fusolin locus, to produce the green fluorescent marker protein (GFP). The growth properties of these recombinant HaEPVs, in comparison to the parental HaEPV, were assessed in cultured Spodoptera frugiperda Sf9 cells. Additionally, GFP production by these recombinant HaEPVs was compared to that of a GFP-expressing recombinant of the baculovirus Autographa californica nucleopolyhedrovirus (AcNPV) in the same in vitro system, at various multiplicities of infection. Expression of GFP from the HaEPV spheroidin locus produced up to 60% of that generated from the AcNPV polyhedrin locus, albeit over a longer period of infection. A considerably lower yield was recorded from the HaEPV fusolin locus, a result that contrasted markedly with the apparent activity of this promoter in caterpillar infections in vivo. The potential applications for further development of HaEPV expression systems are discussed.