B lymphocyte induced maturation protein (Blimp-1) is present in a variety of organisms from nematode to human as a factor carrying well conserved five DNA binding zinc fingers and relatively conserved PR/SET domain. Blimp-1 was found to play important roles in various aspects of development in many organisms andworks mainly as a repressor to suppress many different genes. Blimp-1 inDrosophila was identified as a transcriptional repressor binds to the promoter region of the ftz-f1 gene. To understand the mechanism of how Drosophila Blimp-1 controls expression of its target genes, Blimp-1 was purified from prepared nuclear extract with its interacting proteins. The purified proteins were identified using Liquid chromatography-mass spectrometry (LC-MS/MS) after trypsin digestion. Results of this analysis revealed presence of several peptides of Histone H4 as interacting protein. It could be suggested that Blimp-1 function through a histone-masking mechanism and has an important regulatory chromatin remodeling.