Cystic fibrosis (CF) is produced by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator Gene (CFTR) gene.One hundred twenty eight patients with CF were analysed for mutations in the CFTR gene in order to establish the frequency of CF mutations in the Romanian population. The chief methods of analysis were polymerase chain reaction (PCR) of DNA extracted from blood and electrophoresis of PCR products.The frequency of F508del in CF chromosomes from Romania is approximately 56.3%. Other frequent mutations noted are: G542X (3.9%), W1282X (2.3%), and CFTRdele2,3(21 kb)(1.6%); the remaining mutations have frequencies below 1%.We consider that the frequency of F508del in CF patients from Romania is higher than in previous reports, reaching 56.3%, probably owing to more rigorous selection of patients for genetic testing, allowing improved calculation of mutation frequencies.