A preliminary report of 13 Indian children with cystic fibrosis who were screened for the commonest mutation (delta F 508) is presented. Six (46%) patients were homozygous for delta F 508, while two patients were compound heterozygotes. Thus 14 (53.8%) of 26 mutant chromosomes had delta F 508 mutation. These findings confirm that cystic fibrosis occurs in India and all children with persistent respiratory problems and/or malabsorption should be screened for this disease.