A cDNA clone of about 2300 base pairs was prepared from the human osteosarcoma cell line U-2 OS by hybridization with a 22-mer oligonucleotide complementary to the NH2-terminus of PDGF-A. Restriction and sequence analysis showed that this clone contains the entire coding region for PDGF-A and a long 3'-untranslated region which is only distantly related to that in the mRNA of PDGF-B.