In the review the main advantages in development of the approaches to gene therapy of hereditary diseases are presented. Now more than 1000 genes of hereditary diseases are mapped and some hundreds are cloned which is prerequisite for gene therapy. The transfer of the recombinant gene into the cell and the subsequent expression of the transgene product are the rate-limiting steps for successful gene therapy. A variety of methods, including the use of physical methods, modified viruses and synthetic vectors, are currently being used in experiments and clinical trials. Since the approval and initiation of the first human gene therapy trial to treat ADA deficiency, there have been several dozen approved gene therapy trials but clear clinical result was stated for ADA deficiency only. Cystic Fibrosis, CF was among several hereditary diseases which were considered as a target for gene therapy. Experiments on development of recombinant gene constructions, gene delivery by adenovirus vectors and liposomes as well as by other constructions into epithelial lung cells, gene expression and on the safety of gene therapy procedures were relatively successful. Phase 1 gene therapy clinical trials of CF showed that some unaccounted physiological peculiarities of lung tissue of the patients diminished effectiveness of gene transfer, longevity of CFTR gene expression and in some cases unexpected immunological complications arises during clinical trials. Now an intensive attempt to overcome these problems in gene therapy of CF are undertaken.