A method for detection of the M and Z alleles of the alpha 1-antitrypsin deficiency (AAT) gene has been developed using denaturing gradient gel electrophoresis (DGGE) of DNA samples amplified in vitro by the polymerase chain reaction. Amplification of the 90 nucleotides surrounding the Z mutation site with concurrent attachment of a 40 bp GC-rich region yields DNA fragments that are easily and quickly separated by DGGE. Results are consistently attained in 1-2 days, making this one of the most rapid method of diagnosis of AAT deficiency to date. Additionally, the analyses are completed entirely without the use of radioactive probes, thus eliminating the problems and precautions that are inherent with the use of 32P. The simplicity and reliability of this technique make it well suited for routine use in diagnostic laboratories.