Genes are the smallest functional units of the genetic system, which control the development and function of all organisms. A gene is a linear sequence of DNA that codes for a particular protein. Gene therapy is based on principle that a normal gene is inserted to compensate for a nonfunctional gene and abnormal gene can be repaired through selective reverse mutation. It uses purified preparations of a gene or a fraction of gene to treat diseases. Gene therapy can be used to treat wide range of diseases ranging from single gene disorder to multi-gene disorder. It has variety of applications in the field of dentistry like in cancerous and precancerous condition, salivary gland disorders, autoimmune diseases, bone repair, DNA vaccination, bone repair etc.