We have cloned a contiguous 106×10³ base-pair long stretch of mouse DNA. The isolated chromosomal DNA segment contains the single copy gene Amy-1a that is strongly expressed in the parotid gland and, 23×10³ base-pairs downstream from it, one member of the pancreas-specific Amy-2a oligogene family. At least two of the four Amy-2a genes, including the copy linked to Amy-1a, are efficiently transcribed. The cloned DNA sequences do not appear to specify messenger RNAs other than those encoding alpha-amylase in pancreas, parotid gland or liver. Transcription termination on Amy-1a occurs within 3×10³ base-pairs downstream from the polyadenylation site in both parotid gland and liver, in which this gene is transcribed at different rates from different promoters.