Megestrol (INNTooltip International Nonproprietary Name, BANTooltip British Approved Name) is a progestin of the 17α-hydroxyprogesterone group which was, until recently, never marketed or used clinically. It is now used for treatments of disease-related weight loss, endometrial cancer, and breast cancer. Its acylated derivative megestrol acetate is also a progestogen, which, in contrast to megestrol itself, has been extensively used as a pharmaceutical drug.

As of June 2023, megestrol is being used to treat significant weight loss in HIV/AIDS patients, and as a palliative treatment of endometrial and breast cancers. It can be administered in both tablet and oral suspension forms, with dosages ranging from 100 mg/day to 1600 mg/day depending on the condition being treated.