alpha(1)-Antitrypsin (AAT) deficiency is one of the most common genetic disorders in Caucasians, leading to early onset pulmonary emphysema and/or liver disorders. Accumulating data suggest that AAT deficiency is commonly under-recognized or misdiagnosed by physicians. The need for a rapid, timesaving, and relatively inexpensive but reliable detection method for the two most common deficiency alleles was developed using real-time polymerase chain reaction (PCR) genotyping. We designed and validated a 5'-nuclease assay for typing of the PI*S and PI*Z alleles using dual-labeled target-specific fluorescent probes. As a reference method, we used restriction fragment length polymorphism. The real-time PCR method was tested on a large, cross-sectional epidemiological trial. Overall, we genotyped about 1200 samples and found a very good concordance with AAT serum levels and restriction fragment length polymorphism results. In addition, external interlaboratory validation confirmed the accuracy of the real-time PCR method. In our experience, the real-time qualitative PCR using 5'-nuclease assay is suitable as a genetic test for AAT deficiency. This method offers an acceptable balance between reliability and expenses. It seems appropriate for both population-based screening and clinical diagnosis of the deficiency.