The current study focuses on developing estimates of the numbers of individuals carrying the two most common deficiency alleles, PI*S and PI*Z, for alpha1-antitrypsin deficiency (AT-D) in Europe. Criteria for selection of epidemiological studies were: 1) AT phenotyping performed by isoelectrofocusing or antigen-antibody crossed electrophoresis; 2) rejection of "screening studies"; 3) statistical precision factor score of > or = 5 for Southwest, Western and Northern Europe, > or = 4 for Central Europe, > or = 3 for Eastern Europe; and 4) samples representative of the general population. A total of 75,390 individuals were selected from 21 European countries (one each from Austria, Belgium, Latvia, Hungary, Serbia-Montenegro, Sweden and Switzerland; two each from Denmark, Estonia and Lithuania; three each from Portugal and the UK; four each from Finland, The Netherlands, Norway and Spain; five each from Russia and Germany; six from Poland; eight from Italy; and nine from France). The total AT-D populations of a particular phenotype in the countries selected were: 124,594 ZZ; 560,515 SZ; 16,323,226 MZ; 630,401 SS; and 36,716,819 MS. The largest number of ZZ (5,000-15,000) were in Italy, Spain, Germany, France, the UK, Latvia, Sweden and Denmark, followed by Belgium, Portugal, Serbia-Montenegro, Russia, The Netherlands, Norway and Austria (1,000-2,000), with < 1,000 in each of the remaining countries. A remarkable lack in number of reliable epidemiological studies and marked differences among these European countries and regions within a given country was also found.