To determine the effectiveness of leuprolide acetate depot plus iron compared with iron alone in the preoperative treatment of anemia due to prolonged or excessive bleeding associated with uterine leiomyomas. This was a phase III, stratified, randomized, double-blind, placebo-controlled, parallel-group, 12-week multicenter study. Enrolled patients had hemoglobin levels of 10.2 g/dL or less and/or hematocrit values of 30% or less. Patients were entered into one of two strata based on their pre-study hematocrit level: stratum A, hematocrit less than or equal to 28%, and stratum B, hematocrit greater than 28%. Patients within each stratum were randomized to one of three treatment arms: leuprolide acetate depot 7.5 mg, leuprolide acetate depot 3.75 mg, or placebo. All patients received iron orally. Response was defined as a hemoglobin level of 12 g/dL or more and a hematocrit value of 36% or greater. Three hundred nine patients were entered into the study, of whom 265 were evaluated. Using our response criteria, a significantly greater number of patients in both leuprolide acetate groups (combined strata) responded to therapy than did those in the placebo group: 74% in each leuprolide acetate group versus 46% in the placebo group (P < .001). Gonadotropin-releasing hormone agonist-treated patients had a significant reduction in uterine and myoma volume when compared with the placebo group (P < .01). Hot flashes and vaginitis were reported significantly more often (P < .001) in the leuprolide acetate-treated groups than in the placebo group. Both dosages of GnRH agonist plus iron were more effective than iron alone in treating the anemia of patients with uterine leiomyomas, in reducing uterinemyoma volume, and in alleviating bleeding and other leiomyoma-related symptoms.