The effect of TGF-beta on gene activation in embryonic pancreatic rudiments was investigated using differential mRNA display. Several cDNA bands were augmented and some were suppressed in the presence of TGF-beta. Differentially expressed cDNAs were re-amplified, sequenced, and sequences compared to the GeneBank database. Glucagone and brain alpha-tropomyosin cDNAs were identified from the group of augmented cDNAs, and B-carboxypeptidase form the group of suppressed cDNAs. PCR experiments were confirmed with Northern blots. Obtained results are in accordance with immunohistochemical findings and render differential mRNA display a useful technique in identifying differentially expressed genes in embryonic pancreatic rudiments. Several unknown differentially expressed cDNA sequences obtained in our experiments remain to be identified.