cDNA libraries have been constructed from mRNAs isolated from mature male DBA/2 mouse submaxillary glands. Several recombinant plasmids have been assigned to particular mRNA species and their in vitro translation products by HART and hybrid selection. Clones containing copies of two abundant mRNA species that showed no sexual dimorphism were selected for detailed characterisation. Nucleotide sequences determined from one series of clones define an 850 nucleotide mRNA encoding a polypeptide of 16.5 kd having an N-terminal signal sequence, an acidic core and four glycosylation sites. A second family of clones correspond to an mRNA of 800 nucleotides, the sequence of which can be interpreted as coding for an intracellular protein of 14.7 kd. Computer searches of protein and nucleic acid sequences have not revealed the identity of either of these submaxillary gland products.