So far, more than 1500 mutations have been reported in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Mutational spectrum varies in accordance with geographic and/or ethnic origin. In this study, we have analyzed seven common CF mutations (p.F508del, p.G542X, p.R1162X, p.N1303K, p.R334W, p.R553X and c.3120+1G>A) taking into account the ethnic origin of the Cuban population which is mainly influenced by Spanish and sub-Sahara African contribution. All but p.N1303K have been detected in our patients, the p.F508del being the most prevalent (37.9%). Overall, six mutations showed frequencies above 1% accounting for 55.5% of the Cuban CF alleles.