Dysfunctional uterine bleeding is a disorder which presents problems for effective treatment and management. We have utilized the ability of chronic LRH agonist treatment to suppress ovarian steroid production to examine its effects on stumptailed macaques with a detailed history of excessive days of menstrual bleeding. Five monkeys were treated for 6 months with daily injections of D-Ser[But]6 LRH (1-9) nonapeptide-ethylamide. This was successful in suppressing ovarian steroid production in all monkeys as indicated by the maintenance of serum concentrations of oestradiol at less than 100 pg/ml and progesterone at less than 1 ng/ml. All monkeys menstruated for their typical time period during the first treatment cycle, but thereafter bleeding stopped in 2 monkeys and was considerably reduced in a further 2. In the remaining monkey, no significant improvement occurred. The results indicate that suppression of ovarian function in this way may have a significant role to play in the treatment of dysfunctional uterine bleeding.