Computer programs that can be used for the design of synthetic genes and that are run on an Apple Macintosh computer are described. These programs determine nucleic acid sequences encoding amino acid sequences. They select DNA sequences based on codon usage as specified by the user, and determine the placement of base changes that can be used to create restriction enzyme sites without altering the amino acid sequence. A new algorithm for finding restriction sites by translating the restriction endonuclease target sequence in all three reading frames and then searching the given peptide or protein amino acid sequence with these short restriction enzyme peptide sequences is described. Examples are given for the creation of synthetic DNA sequences for the bovine prethrombin-2 and ribonuclease A genes.