Buserelin acetate, a synthetic analog of gonadotropin-releasing hormone（GnRH）, is widely used　in the treatment of endometriosis and uterine leiomyoma.　This study sought to identify predictors　of side effects of buserelin treatment. The medical records of 52 patients who received buserelin treatment　were reviewed. The patients were divided into　two groups based on the presence or absence of the　common side effects of abnormal vaginal bleeding　and climacteric symptoms, and compared in terms of age, height, weight, BMI, and basal gonadotropin　level. Abnormal vaginal bleeding and climacteric　symptoms were reported in 69.2% and 61.5% of　the patients, respectively. Among patients who did　not report these side effects, mean weight and mean　BMI were significantly higher than those of patients　who reported the side effects. Mean basal level of　serum gonadotropins, the LH:FSH ratio, and patient menstrual history were not related to the incidence　of these side effects. Those with higher weight and　BMI are less likely to have buserelin effects, and　those with lower weight and BMI are more likely　to have these side effects. So, lower weight and BMI might be a predictors for two common side　effects of monthly buserelin treatment.