Genomic integrity of the cancer cell is doubt-full because of fragility on chromosome. Fragile--sites are non-randomly distributed on human genome prone to form gaps or breaks at either pre/or metaphase chromosome arise when cells are exposed to a perturbation of DNA replication process. Cancer cells commonly show various form of "hot spots" including point mutation, chromosome copy number and translocation involving specific gene mutation but the genetic diversity of fragile sites are still not clear. The chromosomal fragile sites (rare & common fragile sites) make the cancer cells not only susceptible to genomic instability but also contribute the process of malignancy due to expansions of microsatellite CGG or AT rich minisatellite. Fragile sites have been implicated due to inter chromosomal amplification events by initiation breakage - fusion cycles. The mechanisms behind these changes give raise to new insight the cytogenetic manifestation of oncogenesis. Fragile sites loci are associated with activation of oncogenesis during cell--cycle analysis. However, these mutations at fragile sites loci might have play a causative or functional role in tumor biology. The topography organization and informatics complexity of the fragile sites remained unexplored due to lack of systematic approach towards molecular cloning of the fragile sites DNA sequences and specific models as not are under taken. The information regarding mode of inheritance of fragile sites are still lacking but the first degree relative specially young proband and maternal side having variable prevalence in different population could be uses as suitable marker for determining genetic predisposition to cancer. This comprehensive review of fragile sites in tumor biology probably helpful to explore to understand the molecular mechanism of carcinogenesis or tumorgenesis.