OBJECTIVE: This study shows the factors influencing the development of postoperative delayed ischemic neurologic deficit. METHODS: The authors analyzed 120 patients had performed aneurysmal neck clipping. Eleven variables were examined as to relationship to delayed ischemic neurologic deficit and classified as non- surgical and surgical variables. Data were analyzed by the univariate analysis and significant variables were entered into multiple logistic regression model in order to draw out Odds ratio. RESULTS: Delayed ischemic neurologic deficit after aneurysm surgery developed in 23 patients(19.2%). Significant non-surgical variables were clinical grade at admission(p=0.032), CT grade(p=0.005), and degree of preoperative angiographic vasospasm. Surgical variables were timing of surgery, brain retraction time, and duration of temporary clip application. The application time of temporary clip was significant (p=0.032) in development of delayed ischemic neurologic deficit. However, in multiple logistic regression analysis, duration of temporary clip application was excluded. With the clinical grade I - II and the CT grade I - II as the reference, the Odds ratio were 2.358(95% CI 0.87-6.37) and 4.041(95% CI 1.06-15.37), respectively. CONCLUSION: Delayed ischemic neurologic deficit after aneurysm surgery developed in poor clinical grade and high CT grade with high risk. The effect of surgery on the development of post-operative vasospasm was not significant.