Articles in the literature on alpha-1 antitrypsin (AAT) deficiency have been interpreted as indicating that AAT deficiency is a rare disease that affects mainly Caucasians (whites) from northern Europe. In a recent publication on the worldwide racial and ethnic distribution of AAT deficiency, new data were presented demonstrating that it is also found in various populations of African blacks; Arabs and Jews in the Middle East; and Central, Far East, and Southeast Asians, as well as whites in Australia, Europe, New Zealand, and North America. The new data on the prevalence of AAT deficiency in other major racial groups worldwide will affect the standards for the diagnosis of AAT deficiency by the medical community, with the realization that is not a rare disease of whites in northern Europe and immigrants from these countries in the New World. In a total population of 4.4 billion in the 58 countries surveyed, there are at least 116 million carriers (those with Pi phenotypes PiMS and PiMZ) and 3.4 million with deficiency allele combinations (phenotypes PiSS, PiSZ, and PiZZ) for the two most prevalent deficiency alleles PiS and PiZ; therefore, the new data suggest that AAT deficiency may be one of the most common serious single-locus genetic diseases in the world. Particularly important is the unique susceptibility of AAT-deficient individuals to exposure to chemical and particulate environmental agents. Such exposures are known to result in both lung and liver disease as well as other adverse health effects.