Chromosomes from 19 unrelated Southern Yugoslav families in which cystic fibrosis (CF) occurs were analysed for the presence of the delta F508 mutation, using polymerase chain reaction amplification followed by dot blot and polyacrylamide gel analysis. Of the 38 CF chromosomes, 15 (39.5%) carry the delta F508 deletion. Restriction fragment length polymorphism haplotypes for KM19/PstI, XV2c/TaqI and J3.11/PstI marker loci were determined and are compared for a total of 34 N and 37 CF chromosomes.