To ascertain whether treatment with a gonadotropin-releasing hormone agonist before endometrial resection reduces absorption of distention fluid and operating time, facilitates the procedure, and improves long-term bleeding pattern, 71 menorrhagic women were allocated to 8 weeks of goserelin depot treatment before operative hysteroscopy or immediate surgery in the early proliferative phase of the cycle. Eight patients withdrew from the study after randomization, leaving 33 in the goserelin arm and 30 in the immediate surgery arm. Mean (SD) operating time was 15.1 (9.0) minutes in the goserelin group versus 16.9 (9.5) minutes in the controls (mean difference 1.8 min, 95% CI -2.9-6.4). Mean (SD) distention medium deficit was, respectively, 422 (287 ml) and 564 ml (291 ml; mean difference 142 ml, 95% CI -4-288). Considering only the 29 women with adenomyosis, the mean (SD) fluid deficit was considerably less in the 19 goserelin-treated group than in the 10 controls, 299 (206) versus 597 (135) ml (mean difference 298 ml, 95% CI 149-447). The surgeons classified intraoperative difficulties as none in 6, minimal in 20, moderate in 7, and severe in no cases in the goserelin group; corresponding figures in the group without pretreatment were 2, 14, 13, and 1 (p = 0.02). At 12-month follow-up 35% of women in the goserelin group were amenorrheic, 23% hypomenorrheic, 42% eumenorrheic, and none hypermenorrheic. Corresponding figures in the immediate surgery group were, respectively, 20%, 30%, 37%, and 13%. Goserelin administration before endometrial resection may reduce absorption of fluid at surgery in some patients and may facilitate intrauterine operating conditions. Effects on long-term bleeding patterns were limited.