Within the scope of an open study, the results after treatment with Buserelin for patients with endometriosis is appraised. The patients are studied by laparoscopy or laparotomy before and after a six-month-long treatment. A clear decline of the endometriosis can be seen; however, endometriomas showed little or no reaction. The Buserelin therapy is shown to be well tolerated. It increases the rate of pregnancies, gives few biochemical complications and is an entirely acceptable therapy with few side effects. Buserelin offers a real alternative for the pharmacotherapy of endometriosis.