Gene therapy is unique technique used in medical treatment that uses specific types of genes to treat several types of diseases. Gene therapy is also used to treat several hereditary diseases, wherein the mutated defective gene is replaced with the functional gene.?Gene therapy is the one which most vast topic carried out by researchers all over the world for the prevent or treat of several diseases such as immune deficiencies, hemophilia, Parkinson’s disease, cancer, and even HIV, through different approaches. Three primary approaches that are being studied and practiced in the gene therapy are replacement of the mutated disease-causing gene with the healthy gene, inactivation of the mutated gene, and introduction of the new gene to fight against the disease. In the gene therapy treatment, a functional gene is inserted into the genome of an individual’s cells and tissues by using a carrier known as ‘vector’. Viruses is the most common type of vectors used in gene therapy, which is genetically altered to carry the normal human DNA. Over the last few years, gene therapy has emerged as a promising treatment option for several diseases including inherited disorders and certain types of cancers and viral infections.