A small but important fraction of cancer are primarily due to a hereditary cancer predisposition, and their diagnosis has significant clinical implications for both index cases and their families. Germline BRCA1BRCA/2 pathogenic variants (PVs) can lead to the Hereditary Breast and Ovarian Cancer (HBOC) Syndrome and identification of both germline and somatic BRCA1/BRCA2 PVs have important treatment implications. In addition, endometrial cancer is closely associated with inherited PVs in the mismatch repair (MMR) genes which leads to Lynch syndrome. Both HBOC and Lynch syndrome affect around 1:300 people, most of whom are undiagnosed. Genetic panel testing is crucial to identifying PV carriers, before a sentinel cancer, who can then be offered prophylactic interventions such as risk reducing salpingo-oophorectomy (RRSO). Within this chapter we discuss the most common hereditary cancer syndromes associated with gynecological cancer. These include HBOC, Lynch syndrome, the moderate penetrant genes including RAD51C, RAD51D, BRIP1, PALB2, and ATM as well as rarer hereditary cancer syndromes including Cowden syndrome (PTEN), DICER1, Rhabdoid Tumor Predisposition syndrome (SMARCB1, SMARCA4) and Peutz-Jeghers syndrome (STK11).