Indirect evidences suggest that the X chromosome in the male germline of many species is inactivated, which might be necessary for the completion of spermatogenesis. The importance of this phenomenon is suggested through its relationship with characteristics of sex chromosomes like the paucity of X-linked male germline transcripts and the unidirectional movement of retroposed genes out of this chromosome. However, there has never been made in Drosophila a direct observation of such hypothetical male germline X-inactivation yet. The interest of my research is to investigate this X-inactivation in Drosophila melanogaster by monitoring X-linked gene expression during developmental phases of spermatogenesis. The genes that are putatively differentially expressed along spermatogenesis will be selected by quantifying mRNA from different phases using a Microarray platform. Two different results are expected from the experiments: a relative decrease of X-linked genes expression along spermatogenesis, indicating germline X-inactivation or no observation of expression decrease at all. Both results represent a significant contribution to the study of X-inactivation.