The geographic distribution and origin of CFTR mutations in Germany was evaluated in 658 three-generation families with cystic fibrosis (CF). Fifty different mutations were detected on 1305 parental CF chromosomes from 22 European countries and overseas. The major mutation. delta F508 was identified on 71.5% of all CF chromosomes, followed by R553X (1.8%), N1303K (1.3%), G542X (1.1%), G551D (0.8%) and R347P (0.8%). According to the grandparents' birthplace, 74% of CF chromosomes had their origin in Germany; the delta F508 percentage was 77%, 75%, 70% and 62% in northern, southern, western and eastern Germany, respectively. Ten or more mutant alleles in the investigated CF gene pool originated from Austria, the Czech Republic, Poland, Russia, Turkey and the Ukraine. This widespread geographic origin of CFTR mutations in today's Germany reflects the many demographic changes and migrations in Central Europe during the 20th century.