Fifty one independent cystic fibrosis (CF) families originating from a restricted area of Southern Italy (Campania) have been analyzed for KM19 and XV2c haplotypes and the delta F508 mutation: 54% of the total CF chromosomes show the delta F508 mutation. No significative correlations were obtained when clinical score, radiological score, Pseudomonas colonization, or clinical symptoms at presentation were matched with the presence or absence of the delta F508 mutation.