Object. The aim of this study was to evaluate the pre- and postoperative rehemorrhage risk, neurological function outcome, and prognostic factors of surgically treated brainstem cavernous malformations (CMs) with long-term follow-up. Methods. The authors conducted a retrospective review of the clinical data from 242 patients with brainstem CMs that were surgically treated between 1999 and 2010. Patient charts, imaging findings, and outcomes were examined. Results. The study included 242 patients, with a male-to-female ratio of 1.3 and mean age of 32.6 years. The mean modified Rankin Scale scores on admission, at discharge, at 3 and 6 months after surgery, and at recent evaluation were 2.2, 2.6, 2.3, 1.8, and 1.5, respectively. The preoperative calculated annual hemorrhage and rehemorrhage rates were 5.0% and 60.9%, respectively. The complete resection rate was 95%. Surgical morbidity occurred in 112 patients (46.3%). Eighty-five patients (35.1%) demonstrated worsened condition immediately after surgery; 34 (41.0%) and 51(61.4%) of these patients recovered to their baseline level within 3 and 6 months after surgery, respectively. At a mean follow-up of 89.4 months, the patients' condition had improved in 147 cases (60.7%), was unchanged in 70 cases (28.9%), and had worsened in 25 cases (10.3%). A total of 8 hemorrhages occurred in 6 patients, and the postoperative annual hemorrhage rate was 0.4%. Permanent morbidity remained in 65 patients (26.9%). The adverse factors for preoperative rehemorrhage were age >= 50 years, size >= 2 cm, and perilesional edema. The risk factors for postoperative hemorrhage were developmental venous anomaly and incomplete resection. The independent adverse factors for long-term outcome were increased age, multiple hemorrhages, ventral-seated lesions, and poor preoperative status. Favorable, complete improvement in the postoperative deficits over time was correlated with good preoperative neurological function and continuing improvement thereafter. Conclusions. Favorable long-term outcomes and significantly low postoperative annual hemorrhage rates were achieved via surgery. Total resection should be attempted with an aim of minimal injury to neurological function; however, postoperative deficits can improve during the postoperative course. Close follow-up with radiological examination is proposed for patients with adverse factors predictive of rehemorrhage.