Although chronic subdural hematoma (CSDH) is one of the most common entities encountered in neurosurgical practice, optimal surgical treatment for CSDH remains controversial. This study retrospectively compared results for CSDH between burr hole drainage alone and burr hole drainage with irrigation. Ninety-two patients with CSDH underwent surgery at our institution from January 1998 through December 2009. Fifty-eight patients received burr hole drainage alone (Group A), while 34 patients were treated using burr hole drainage with irrigation (Group B). Outcomes, recurrence rates, and death rates for the two groups were analyzed. Age, sex ratio, consciousness level on admission, radiodensity of hematoma on computed tomography before surgery, and duration of hospitalization were nearly the same in both groups. No significant differences were seen in good outcomes or death rates between groups, but poor outcomes were significantly more frequent in Group A (p=0.009). The recurrence rate was higher in Group A compared to Group B (10.3% vs. 2.9%). The authors used logistic regression analysis to identify factors associated with the outcome of CSDH, and found that duration of hospital stay, anti-coagulant therapy, presence of dementia and burr hole drainage alone were significantly associated with poor outcome of CSDH. These results indicate that burr hole drainage with irrigation has a significantly stronger association with good outcomes compared to drainage alone, and could be a reliable and effective operative method for the treatment of CSDH with a lower recurrence rate.