The G551D mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) is the third most common allele found in cystic fibrosis patients. This mutation is a single base pair substitution at the 551^st codon of the CFTR gene that leads to a substitution of glycine (GGT) by aspartic acid (GAT). DNA detection of such a mutation can be achieved through polymerase chain reaction (PCR) amplification utilizing allele-specific primers. In testing a more reliable approach to a diagnostic assay, an intentional mismatch strategy as described by Hidenobu Yaku’s group was applied to the oligonucleotide design in an attempt to decrease the number of false positives encountered and a third nested primer was added to further confirm the amplified region.