An analysis of 274 non-delta F508 Italian cystic fibrosis chromosomes was carried out to determine their molecular defect. In a first step, the delta F508 and 59 other mutations were detected by polyacrylamide gel electrophoresis, restriction digestion, and the amplification refractory mutation system (ARMS) technique. The molecular defects of the other chromosomes were screened for by denaturing gradient gel electrophoresis analysis of exons 3, 4, 7, 11, 12, 13, 14a, 17b, 19 and 20. Direct sequencing was carried out if necessary. This approach allowed us to identify 3 novel mutations, namely M348K, D614G and F693L.