Objective Sentinel headache (SH) is considered as a signal of the impending rupture of an aneurysm. However, it is difficult to diagnose whether the headaches of patients are associated with unstable aneurysms. Therefore, there is some doubt about the importance of headaches in patients with unruptured intracranial aneurysms (UIAs). This study was performed to explore the existence and clinical characteristics of SH associated with aneurysms. Methods Thirty-six patients with a single UIA were collected in this study. Patients were symptomatically categorized into two groups: SH and non-SH. The PHASES scores and patient and aneurysm characteristics were analyzed. Two independent MRI experts who were blinded to the patients’ clinical history conducted the analysis of the SWI results. Results There were 15 patients with sentinel headache. No significant difference was found in patient’s basic information and history. The SH group had a higher PHASES score than the non-SH group (P < 0.05). In univariable analysis, abnormal SWI signals were significantly more frequent in the SH group (P < 0.01) and the inflow angle was significantly lower in the non-SH group (P < 0.05). In multivariable analysis, abnormal signals in SWI were an independent factor associated with SH (P < 0.01). Conclusions SH exists in patients with UIAs and may indicate a high risk of aneurysm rupture. Abnormal signals on SWI may serve as a clinical feature to identify aneurysm-related SH and be helpful for the formulation of therapeutic strategy. Aneurysm geometry may also be related to SH but need further studies in the future.