Cancer and its treatment often have an impact on patients’ sexuality, affecting both their sexual desire and, in some cases, sexual function. In some patients, sexual problems may be temporary, while in others their effects can be long-lasting. The National Cancer Institute’s (NCI) Web site provides peer-reviewed summaries of information about the sexual-related side effects of cancer treatment. Here, you will find information about some of the common sexual changes that occur during and after cancer treatment, including surgery, radiation therapy, chemotherapy, and hormone therapy. You can also learn about how sexual problems are assessed and treated in cancer patients, as well as how cancer treatment may affect fertility. These summaries are available in two formats — for patients and for health professionals — and in Spanish. You may want to begin with the patient version, but the version for health professionals is more comprehensive and suited for someone who is familiar with cancer. This version also refers to key citations in the medical literature that link to published medical journal abstracts.