We have determined the nucleotide sequence of regl a human genomic DNA fragment homologous to the reg gene which is expressed in the exocrine pancreas and regenerating islets. Sequence comparisons of reg and regl suggested similar exon-intron organisation. Based on this assumption, specific oligonucleotides for regl exons were used to demonstrate expression of the regl gene in pancreas and liver. The proteins encoded by reg and regl comprise 166 amino acids and differ by 22 amino acids only.