Human bone marrow mesenchymal stem cells (hMSCs) give rise to adipocytes in response to adipogenic hormones. An in-house cDNA microarray representing 3400 genes was employed to characterize the modulation of genes involved in this process. A total of 197 genes showed temporal gene expression changes during adipogenesis, including genes encoding transcriptional regulators and signaling molecules. Semi-quantitative RT-PCR analyses confirmed differential expression at the transcriptional level of several genes identified by cDNA microarray screening. Cluster analysis of the genes regulated during the late phase (from day 7 to day 14) of hMSC adipogenesis indicated that these changes are well correlated with data previously reported for murine preadipocytes. However, during the early phase (day 1-day 5), the modulations of genes differed from those reported for the preadipocytes. These data provide novel information on the molecular mechanisms required for lineage commitment and maturation accompanying adipogenesis of hMSC.