Diseases caused by viruses especially Monodon baculovirus (MBV) are still challenging to worldwide shrimp culture. Study on genetic variation of the virus is critical for controlling vinls infection as well as development of vaccines and vaccination strategies. Here in, the authors reported the results of cloning and sequence analysis of a gene coding for Polyhedrin, the major constituent protein of occlusion bodies of Monodon baculovirus (MBV) which has been shown to prompt immune responses and considered one of the major immunogenic proteins from MBV. The polhed gene of MBV is 1375 base pair in long and encodes a protein of 457 amino acids. The result of sequence analysis showed that polhed from Vietnam has 96 percent and 93 percent nt sequence homology compared to that of Thailand (EU251062) and India (JN194201.1), respectively. Notably, the authors found that the polyhedrin from Vietnam has an extra domain (from aa 73 to 96) that was not present in that of Thailand. In addition, the authors also observed other aa substitutions in the protein sequence as: Thr - Gly (aa 55), Glu - Asp (aa 63), Asn - Asp (aa 72, Glu - Gly (aa 92), Met - Leu (aa 93), Lys - Asn (aa 108 and 113) compared to that of Thailand. This study provides new information concerning the genetic variability of the MBV speading in paneaus monodon in Vietnam.