Hereditary nonpolyposis colorectal cancer, or Lynch syndrome, is responsible for 2–3% of all colorectal cancers. Lynch syndrome is also associated with a high risk of extracolonic cancers, including endometrial, stomach, small bowel, pancreas, biliary tract, ovary, urinary tract, brain, and skin cancer. In this Review, we discuss the risks, surveillance tests, and guidelines for the management of extracolonic tumours associated with Lynch syndrome. For all types of extracolonic cancer, evidence supporting surveillance is scarce. A benefit of surveillance is evident only for endometrial cancer, where transvaginal ultrasound and endometrial sampling detect tumours in early stages. Surveillance is generally recommended for urinary tract and gastric cancer, especially in families with more than one member with these types of cancer. For the other types of cancer, surveillance is typically not recommended. Prophylactic hysterectomy and bilateral salpingo-oophorectomy should be considered for women with Lynch syndrome who are past childbearing age, especially during surgery for colorectal cancer. No data show efficacy of chemopreventive drugs in reducing the risk of extracolonic cancers for patients with Lynch syndrome.