This article describes the prospects of gene tharapy of blood disorders, cancer, HIV infection and cystic fibrosis. The article outlines the approaches currently explored for gene therapy of these diseases and experimental details are not mentioned except for their conclusion. The Sickle cell anemia and beta thalassemia have been cured in mice and rabbits by gene therapy. The monkey virus is the gene transfer vector and kidney cells are the target cells. The clinical trials for the gene therapy of hemophilia B have been carried out in human beings with some success. In the gene therapy of cancer, cytokine genes, specific drug activating genes, and alteration of immune response to the cancer are the major approaches, currently explored. The gene therapy for HIV infections appears to be cotherapy, to be used in lower magnitudes of infections with other therapies. The causative mutation for the cystic fibrosis has been identified and the research is directed towards construction of an artifical chromosome which will act as a vector for transfer of therapeutic gene.