Womb (uterine/endometrial) cancer is a fairly common disease affecting approximately 1 in 70 women. A hysterectomy is usually curative because most cancers have a low risk of spreading (metastasising) to other sites which may result in a later recurrence. Microscopic examination of the hysterectomy specimen can tell doctors if there is a high risk of the cancer returning and this allows women to decide if they want further preventative treatment (adjuvant therapy) to reduce the risk. Chemotherapy can increase cure rates for other types of high-risk cancer after initial surgery and this review examines the effectiveness of chemotherapy for primary womb cancer after hysterectomy. Data from nine high quality randomised clinical trials involving up to 2197 women were subjected to systematic statistical modelling. This shows that chemotherapy reduces the risk of recurrent disease, lengthens the duration women have before a metastasis is diagnosed and improves survival rates. There are many ways to examine the data. The subset analysis that excluded old fashioned drug regimens suggests that chemotherapy reduces the risk of being dead at any nominated time by a quarter. The number of women who would need to have need chemotherapy to prevent one death depends on the type of cancer. In these trials, one woman was cured for every 25 women treated with high dose platinum based chemotherapy after hysterectomy. This is an absolute risk reduction of 4%. Chemotherapy is associated with a greater survival advantage than radiotherapy and has added value when used with radiotherapy. It also appears to reduce the absolute risk of developing a recurrence outside the pelvis by about 5%. This would benefit one woman in every 20 treated. However, chemotherapy has side effects, risks and temporarily reduces a woman's quality of life. In many cases, the small reduction in the cancer recurrence risk may not be worth the side effects of adjuvant treatment.