Background: Alpha-1-antitrypsin (AAT) has many different genetic variants but the most prevalent alleles that cause AAT deficiency are S and Z variants. The allele frequencies of AAT variants, have been identified in many countries but there were not any statistical reports on Iranian population. Therefore, the aim of this study was to investigate the frequency of M1, M2, M3, S and Z variants in Iran.Materials and Methods: In this study 318 sera were obtained from healthy volunteer students of Tehran universities dormitories using ethnic stratified sampling. Then phenotyping was carried out by isoelectric focusing (IEF) with pharmalite pH= 4.2-4.9 in comparison with standard phenotypes. Results: From 318 normal sera, 201 had M1, 55M2, 41M3, 8MS, and 6 MZ phenotypes, 7 sera had other phenotypes.Conclusion: Allele frequency of M1, M2, M3, S, Z and other variants of AAT in the population of Iran were 0.6477, 0.1776, 0.1305, 0.0126, 0.0094 and 0.0220 respectively.