Mast cells play an important role in allergic inflammation by releasing their bioactive mediators. The function of mast cells is enhanced by stimulation because of the induction of specific genes and their products. While many inducible genes have been elucidated, we speculated that a significant number of genes remain to be identified. Thus, we applied differential display (dd) PCR to establish a profile of the induced genes in bone marrow-derived mast cells (BMMCs) after they were co-cultured with 3T3 fibroblasts. To date, 150 cDNA fragments from the connective-type mast cells (CTMCs) were amplified. Among them, thirty cDNA fragments were reamplified for cloning and sequencing. The ddPCR strategy revealed that serine proteases were the most abundant genes among the sequenced clones induced during the maturation. Additionally, unknown genes from the co-culture of BMMCs with 3T3 fibroblasts were identified. We confirmed their induction in the CTMCs by Northern blot analysis and RT-PCR. Characterization of these induced genes during the maturation processes will provide insight into the functions of mast cells.