Turner syndrome (TS) is a common genetic disorder, resulting from the partial or complete absence of one sex chromosome, and occurring in approximately 50 per 100,000 liveborn girls. TS is associated with reduced adult height and with gonadal dysgenesis, leading to insufficient circulating levels of female sex steroids and to infertility. Morbidity and mortality are increased in TS but average intellectual performance is within the normal range. A number of recent studies have allowed new insights to be gained with respect to epidemiology, genetics, cardiology, endocrinology and metabolism. Elucidation of the effects of short stature homeobox protein deficiency has explained some of the phenotypic characteristics in TS, principally short stature. Treatment with growth hormone during childhood and adolescence allows a considerable gain in adult height, although the consequences of this treatment in the very long term are not clear. Puberty must be induced in most cases, and female sex hormone replacement therapy (HRT) is given during adult years. The optimal dose of HRT has not been established and, likewise, the benefits and drawbacks of HRT have not been thoroughly evaluated. The risks of type 2 diabetes, type 1 diabetes, hypothyroidism, osteoporosis, congenital heart disease, hypertension, ischemic heart disease, aortic dilatation and dissection, inflammatory bowel disease and celiac disease are clearly elevated, and proper care during adulthood is important. Currently no firm guidelines for diagnosis exist. In conclusion, TS is a condition associated with a number of diseases and conditions that are reviewed in the present paper. Individuals with TS need life-long medical attention.