Objective: Intracranial pressure (ICP) is frequently elevated following aneurysmal subarachnoid hemorrhage (aSAH). In this prospective study, the factors associated with increased ICP and the relationship between ICP and the aSAH grade were evaluated. Methods: Consecutive patients with prospective aSAH were enrolled within 24 h after disease onset. Clinical scoring, including the Hunt and Hess scale, the WFNS scale and the Fisher scale, was performed upon admission. Consciousness was evaluated based on the Glasgow Coma Scale, and the subarachnoid hemorrhage volume was determined according to a CT scan. Then, an ICP monitor was placed, and ICP was recorded. The relationship between ICP and the aSAH grade was examined using Spearman correlation coefficients. Additionally, some clinical characteristics of the patients, including age, sex, location and size of the aneurysm, hydrocephalus and rebleeding, were recorded and analyzed. Results: A total of 165 patients were enrolled in this study. Of these patients, 111(67.2%) displayed elevated ICP >= 20 mm Hg). The patients who underwent intubation or who experienced rebleeding or hydrocephalus displayed an elevated ICP compared with those who did not (P = 0.002, P = 0.001 and P = 0.008, respectively). There was a positive linear correlation between ICP and both the Hunt and Hess grade and the WFNS grade (correlation coefficients of 0.731 and 0.761, respectively). The correlation between ICP and the Fisher grade was weak according to the correlation coefficient of only 0.093. Conclusion: ICP following aSAH positively correlates with the patient's consciousness, but no relationship was detected between ICP and the subarachnoid hemorrhage volume. (C) 2014 Elsevier B.V. All rights reserved.