Cystic Fibrosis (CF) is an autosomal recessive disease that significantly affects quality of life and lifespan. There are currently no effective animal models of CF that mimic the human disease state. This prevents the development of pharmaceutical treatments for patients. Sheep have been considered for a useful animal model because of their size, life expectancy, and similarities in their anatomy and physiology. In order to generate a sheep transgenic model to study CF we have produced two Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene targeting DNA vectors containing large regions of homology to the CFTR gene in sheep. One of these targeting vectors (ΔF508Neo) contains sequences designed to delete the phenylalanine at amino acid position 508 of CFTR. Another targeting vector (G27XDTNeo) contains sequences designed to introduce an early stop codon into the CFTR gene such that no CFTR is produced. These two targeting vectors were used to transfect White Romney fibroblast cells. Donor sheep oocytes were collected for use in somatic cell nuclear transfer (scNT) with the two genetically modified cell lines. Embryos produced from scNT were transferred to recipient ewes which resulted in the birth of 11 ΔF508 heterozygous lambs and 3 G27XDT heterozygous lambs