Turner syndrome (TS) is due to complete or partial X-chromosome monosomy. The main risk of cancer in this syndrome is for gonadoblastoma, in cases with evidence of some Y chromosome lineage. However, the risk may only be 7–10 % and may have been overestimated in the past (Gravholt et al. 2000). The cumulative risk has been found to be 7.9 % by age 25 in this group of patients (Schoemaker et al. 2008). The risk of breast cancer is significantly decreased in TS (SIR 0.3 [0.2–0.6]). Tumours of the CNS, especially meningioma and childhood brain Tumours, appear to occur with increased risk in TS (meningioma SIR 12.0 [4.8–24.8], childhood brain Tumours 10.3 [2.1–30.1], cancers of the bladder and urethra 4.0 [1.3–9.2] and eye 10.5 [1.3–37.9]), and there may also be increased risks of melanoma, SIR 2.2 (95 % CI 1.0–4.4), and of corpus uteri cancer especially at ages 15–44 years ( SIR 8.0 [1.6–23.2], compared with the general population, with a cumulative risk of 7.9 % (95 % CI 3.1–19.0) by age 25 years in this group (Schoemaker et al. 2008).