Exacerbation of certain medical conditions at specific phases of the menstrual cycle is a well-recognized phenomenon. We review the effects of the menstrual cycle on medical conditions, including menstrual migraine, epilepsy, asthma, rheumatoid arthritis, irritable bowel syndrome, and diabetes. We discuss the role of medical suppression of ovulation using gonadotropin-releasing hormone agonists in the evaluation and treatment of these disorders. Peer-reviewed publications from English-language literature were located via MEDLINE or from bibliographies of relevant articles. We reviewed all review articles, case reports and series, and therapeutic trials. Emphasis was placed on diagnosis and therapy of menstrual cycle-related exacerbations of disease processes. Abrupt changes in the concentrations of circulating ovarian steroids at ovulation and premenstrually may account for menstrual cycle-related changes in these chronic conditions. Accurate documentation of symptoms on a menstrual calendar allows identification of women with cyclic alterations in disease activity. Medical suppression of ovulation using gonadotropin-releasing hormone agonists can be useful for both diagnosis and treatment of any severe, recurrent menstrual cycle-related disease exacerbations.