To initiate the complete characterization of mutations in the CFTR gene in Greek cystic fibrosis (CF) patients, we screened 184 patients for six relatively common mutations (delta F 508, G542X, G551D, 621 + 1 G-->T, N1303K, W1282X) using allele-specific hybridization and, in addition, analyzed exons 4, 5, 7, 8, 10, 11, 17b, 19, 20 and 21 using the method of denaturing gradient gel electrophoresis (DGGE). Six mutations accounted for 65.9% of the CF alleles in Greek patients, of which the delta F 508 mutation had a frequency of 52.7%. A further 15 previously described mutations accounted for another 8.3% CF alleles and one previously undescribed mutation (3272-4A-->G) was found in one chromosome. The W1282X mutation was not detected at all. Thus, so far, we have identified 21 mutations in the CFTR gene in Greek CF patients, accounting for 74.5% of the CF alleles.