The current study focuses on updating estimates of the numbers of individuals carrying the two most common deficiency alleles, protease inhibitor (PI)*S and PI*Z, for alpha1-antitrypsin deficiency (AT-D) in 20 Asian countries. A total of 170 cohorts with 31,177 individuals were selected from 20 Asian countries. The total AT-D populations in the countries selected were: 7,264 ZZ; 36,754 SZ; 6,672,479 MZ; 46,492 SS; and 16,881,108 MS. Marked differences among the Asian countries and regions were also found for the prevalence of the deficiency alleles PI*S and PI*Z. These numbers demonstrate that AT-D is not just a genetic disease that affects smaller numbers than various countries, for example, in Europe. There were marked differences between the prevalence of the PI*S and PI*Z deficiency alleles among these 20 Asian countries as well as among the countries within a given geographic region in Asia. The largest numbers of ZZ phenotypes (3,000-14,000) were in Afghanistan, Pakistan, Saudi Arabia and Thailand; with <1,700 in each of the remaining countries.