DNA is the active ingredient of all the biological operations of the cell because it stores genetic information in the configuration of genes. It is a very well recognized fact that DNA has a double-helical structure; recently, it was reported to have another unusual four-stranded form at the genome of living cells. Generally, G-quadruplexes are located in human telomeres and oncogene-promoter regions where guanine is abundantly present. Recently, DNA G-quadruplexes have been used for the novel molecular target for cancer treatment. They have been regulated and targeted in different ways with many proteins and drugs. G-quadruplex ligands can disable the enzymatic activity of telomerase, which is overactive in cancer cells. G-quadruplex has a fused ring arrangement, which is capable of heaping on the interface of the terminally present G. It is an extraordinarily stable and rigid structure abundantly found when cells are ready to divide normally. Cancer cells divide rapidly, cause defects in their telomeres. The G-quadruplex is an important form in cancer cells where G-quadruplex ligands can bind and inactivate the activity of the telomerase enzyme. This has strategized by targeting G-quadruplex to prevent the replication of DNA that will ultimately block cell division in cancer cells.