ORF 29 of Bombyx mori nucleopolyhedrovirus (BmNPV ORF29), a conserved gene among all the lepidopteran baculoviruses, was subjected to analysis of sequence and transcription/translation in the insect BmN cells in vitro. His-tagged BmNPV ORF29 fusion protein was expressed in Escherichia coli, purified and used for the production of an antiserum. All the homologs of BmNPV ORF29 in baculoviruses contain a Nudix motif with slight modifications in the N-terminal part. A 654 nts-long transcript of BmNPV ORF29 in BmN cells was detected at 3-48 hrs p.i. indicating the early nature of the gene. In the virus-infected cells, the BmNPV ORF29 protein of 26 K was present in both the cytoplasm and nucleus. In the virions, the protein was present in Budded virus (BV), but not in Occlusion-derived virus (ODV). These results suggest that BmNPV ORF29 is a functional ORF of BmNPV, which encodes a 26 K protein expressed in the early stage of infection cycle.