About 5-10 % of cancer diseases may be caused by genetic predisposition, in ovarian cancer it could be almost 20 % of cases. The cause is mostly a pathogenic germline mutation in tumor suppressor genes, DNA repair genes, less frequently in oncogenes. So far, we know more than 200 hereditary cancer syndromes. The most frequently tested are hereditary breast and ovarian cancer syndrome, hereditary nonpolyposis colorectal cancer (Lynch syndrome), quite frequent are also hereditary gastrointestinal polyposes. Genetic counseling and testing are routinely available for patients or their relatives. Testing methods are changing; nowadays we use next generation sequencing methods (massive parallel sequencing) with testing of panels of high-risk genes. If the mutation is discovered, we may offer the testing to relatives. Genetic testing is indicated by medical geneticist after the genetic counseling session. High-risk individuals should be followed oncology clinics or by other specialists.