We have isolated from a rat brain lambda gt11 expression library two overlapping cDNA clones of sizes 2.5 and 3.0 kb corresponding to the heavy neurofilament polypeptide (NF-H). The 2.5 kb insert apparently represents virtually the whole of the C-terminal tail, the 3.0 kb insert also encodes the conserved epitope for the monoclonal antibody, anti-IFA. The identity of the cDNAs was established by comparison of the predicted amino acid sequence with the known partial amino acid sequence of porcine NF-H. A repeat peptide sequence that may be a multiphosphorylation site was identified in the C-terminal non-helical tail.