Dienogest (Visanne®) is a synthetic oral progestogen with unique pharmacological properties that is indicated at a dosage of 2 mg/day for the treatment of endometriosis. It is generally highly selective for the progesterone receptor and displays strong progestational effects and moderate antigonadotrophic effects, but no androgenic, glucocorticoid or mineralocorticoid activity. Dienogest has moderate affinity for progesterone receptors (10% that of progesterone) and at a dosage of 2 mg/day only moderately suppresses estradiol levels. It has high oral bioavailability and a half-life suitable for once-daily administration. In randomized clinical trials, oral dienogest was significantly more effective than placebo in reducing pelvic pain in patients with confirmed endometriosis. In trials comparing oral dienogest for 16 or 24 weeks with gonadotropin-releasing hormone (GnRH) agonists commonly used in the treatment of endometriosis, dienogest was noninferior to depot leuprorelin in reducing pelvic pain and was not significantly different from intranasal buserelin and depot triptorelin in improving combined symptoms/signs scores or revised American Fertility Society (rAFS) staging scores, respectively. Improvements were also noted in some measures of health-related quality of life. The efficacy of dienogest was sustained during long-term treatment for more than 1 year. Dienogest was generally well tolerated and was not considered to be associated with clinically relevant androgenic effects. It appeared to have fewer hypoestrogenic effects than the GnRH agonists. Dienogest was associated with a high incidence of abnormal menstrual bleeding patterns, although this was generally well tolerated by patients, with few discontinuing therapy, and the bleeding intensity and frequency decreased over time. Therefore, oral dienogest offers an effective, generally well tolerated therapeutic option for the long-term treatment of endometriosis.