During their transit through the epididymis, spermatozoa undergo many biochemical modifications necessary to acquire flagellar motility and fertilizing ability. These modifications, collectively called sperm maturation, are well orchestrated along the epididymis and depend on highly regionalized gene expression patterns. Based on clinical observations, the role of the epididymis in human sperm maturation has been questioned. To further understand the function of the excurrent duct in humans, we analysed gene expression of three donors on 'Affymetrix human GeneChip U133 plus 2' representing 47,000 transcriptional variants. More than 50% of transcripts were detected in each epididymal region. The analysis of hierarchical clustering performed from 2274 modulated qualifers between the three regions revealed that 1184, 713 and 269 were highly expressed in the caput, corpus and cauda region, respectively, in a very specific manner. The expressed qualifers were grouped according their similarity by Gene Ontology to give an overview of the functional features of the encoded proteins and to elucidate their potential roles in the epididymis. Northern blot analysis of eight gene transcripts predicted by microarray data to be highly expressed in the human epididymis was performed. All the transcript expression patterns confirmed the microarrays results. The data generated in this study demonstrate a region-specific gene expression pattern along the human epididymis that seems to coincide with the morphologically distinctive features of the excurrent duct.